Ask Onpay for refund, as your payment cannot be processed by our billing.
What you did is the following:
After you opened billing and selected payment system, you were redirected to Onpay page. Then, after clicking "Pay" button, you have copied the link and paste it to the other browser. You paid loosing session, i.e. you seemed to transfer money to our Onpay account but without info about yourself, to which account shall money be deposited, etc. As a result, money has been deposited, but our system does not know who is the owner of the money.
Our advice: ask Onpay on refund. Wait until the amount is refunded and pay again but strictly following step by step instructions (VIA billing, not changing browsers).
Though, I am not sure that you will do that.