Assuming that your question pertains to a Credit Card transaction, worry not. Your experience is fairly common worldwide.

Credit Card Issuer Banks (HDFC Bank in this case) use Fraud Detection & Prevention (FD&P) software to, well, detect and prevent fraud in credit card transactions.

It’s beyond the purview of this answer to go into the details of these systems but suffice to say that, very few banks are in a position to overcome the serious technology, UX and cost challenges involved in preventing a fraud from happening.

So, in actual practice, most banks let a credit card transaction go through (“authorize”) even if their FD&P software suspects it to be fraudulent before-the-fact, and confirms it to be fraudulent after-the-fact. In your case, you, as the credit cardholder learned about the transaction and raised a dispute, which means that the said transaction was authorized i.e. not prevented before the fact.

Even a transaction that was found to be a fraud after-the-fact will be posted to your account since it was authorized. Accordingly, it will appear on your monthly credit card statement. This is true regardless of whether you spotted the fraudulent transaction and / or raised a dispute against it. This is a fundamental fact of the credit card industry. Ergo, I said worry not in the beginning.

Some banks will, by themselves, also post a reversal entry in the same statement since they ascertained that the transaction was fraudulent. This is the best case scenario for the cardholder: No action required, no monetary loss caused by fraud.

Some banks will post a reversal entry in the same statement only if you spotted the fraudulent transaction and raised a dispute before the statement was generated.

Some banks won’t post a reversal entry in the same statement even after they have ascertained that the transaction was fraudulent, whether or not you raised a dispute. There are two ways to go from here:

(a) If you spot the fraudulent transaction in the statement, you need to raise a dispute again. Most probably, the bank will reverse this charge in the next monthly statement.

(b) If you don’t spot the fraudulent transaction in the statement, you will pay the amount, and the bank will coolly pocket the money. This is the worst case scenario for the cardholder: Loss of money due to fraud.

In many industries, (a) and (b) would be called shady practices or dark patterns and blockaded by the regulator.

But this is how banks operate. I’m saying this based on my experience of dealing with dozens of banks in half a dozen countries. And, sadly, fintechs have not been able to change the reality.

So, my recommendation is, just chill and repeat your dispute to your bank.

UPDATE-1:

I had my above answer reviewed by an ex-Banker who is familiar with the credit card dispute and customer complaint redressal process. They averred that I’ve covered the dispute process accurately but suggested the following addition:

If the Credit Card Issuer Bank takes it as a disputed transaction, then in some cases temporary credit won’t be given unless it wins the case with the merchant. But it will flag the transaction as a dispute. It means the transaction will still appear in the statement but with a flag in it. The specific action is also influenced by whether the Cardholder has or does not have previous history with said Merchant.

UPDATE-2:

Copy-pasting key comments.

Hello sir….i need some guidelines as i have faced fraud on my credit card and rbl bank is simply stating it otp based so customer is liable to pay….i hve only received fromal call of 2 mints from investigating dept of rbl. I have filed again complaint for to the customer care stating i m not satisfied.
You can ask the bank to show evidence that you have received the said OTP on the registered mobile number of the said account and that you have entered it to complete the transaction. In return, the bank can ask you to show evidence that you have not received the OTP and not entered it. Only a lawyer can advise whether the burden of proof lies on the bank or you.

On a side note, if you remove typos from your comment, you might get more response. Many people simply don’t bother to respond to requests for help containing typos because they believe that if the help-seeker can’t even make the small effort to keep their comment typo-free while seeking help from others, then they s/he won’t be able to make the larger effort to follow their advice, so why waste time giving it.

I reported to them stating it’s an Unauthorized Transaction, they closed the complaint stating it was an OTP enabled transaction.

I am not getting how should i deal with them.

Credit card department are only available on customer care.

Well, if the bank claims that the said credit card payment was enabled by OTP, then your way forward depends on whether you did indeed receive the said OTP on the registered mobile number of the said account and whether you – or your agent – entered it to complete the transaction.

If you did not, then it’s clearly a case of credit card fraud and the bank is liable to reverse the debit.

If you did, then it’s not a case of credit card fraud but you still have grounds to seek a refund from your bank under the “Deficiency of Service” credit card rule – provided some conditions are met, as explained in Ketharaman Swaminathan’s answer to There was a fraud transaction on my credit card and I told OTP to him by mistake. Can I get the refund or not?

As for who bears the burden of proof for what they’re claiming, see my previous comment.

Banks in India have managed to pull wool over the eyes of gullible public and make them believe that OTP protects customers’ interest – when in fact it protects the bank’s interest. As a result, during your pursuit of reversal / refund, be prepared to face a lot of pushback from the bank and sly comments on social networks from random jokers who have gotten conned by banks but don’t know it yet. Provided the aforementioned conditons are met, credit card rules are weighted towards the cardholder, so perseverance will finally pay. Best wishes!