I seriously doubt if you can complain to anyone.
Cross border payments flow through multiple banks across multiple jurisdictions, thereby falling out of the jurisdiction of any single regulator. Even if different regulators have jurisdictions over the different legs of such a transaction, you may lack locus standi to complain to all of those regulators.
IMO, you should simply switch your business to the bank that gives you the best deal.
In a free market, choice is aplenty. Customers vote with their wallet instead of seeking someone to complain to – unless there’s an egregious breach of contract, which, I presume, is not the case in your situation.
#FreeMarkets #CrossBorder #Regulator