BTC to BNB swap

COST TO BE DETERMINE AFTER WE DISCUSS THE DETAILS......I need a swap feature at my web page (app) so as to swap BTC to BNB. I want to be able to charge a fee and the user will pay the txn costs. I sell a service and the users need to pay for it using BNB. So to make it easy on the user, I want them to be able to get BNB at my website.