Interest on a bank account

I received interest on my bank account, and now I find out that there is a halachic problem with that. What am I supposed to do now? Thank you very much

Approach a bank teller and tell him that you don’t want the interest money. The teller will tell you that there is nothing he can do about it. Now you can use the money. In this case, you said that you didn’t want the interest, but the body that paid you the interest voluntarily let you have it. (The bank teller, who was hired by the owners of the bank, has the authority to give you a free gift.) Now you are allowed to use the money.

Shulchan Oruch, section Yore Dea, ch. 160, §5