Is it permissible to deal with a usurious bank if the client waives some specifications in exchange for a difference in price and agrees to these differences, and if it is not permissible, what should be done with the money acquired?

A letter of credit is considered a usurious and forbidden loan if the client does not possess the full value of the credit and the bank lends it to him with interest. The buyer's waiver of certain specifications for the purpose of commercial fraud is forbidden. Cooperation with these parties is forbidden because it is cooperation in sin and aggression. Money acquired from forbidden transactions, if its acquirer repents and was ignorant of its prohibition at the time, then there is no sin upon him in benefiting from it, but it is better to spend it on charitable causes.