Discovery Bank - **********ly opening new account & unable to assist in closure

Having paid up and closed my Discovery Credit Card account in April, Discovery Bank has proceeded to open another account. Despite numerous phone calls and emails I have now received sms confirming that I owe them money on the new account? I overpaid the settlement in April and they even refunded me the difference. No one at Discovery Bank is able to explain how this has happened and I have repeatedly confirmed that I do not want the new account. It seems as though they have **********ly opened a new account. I am shocked as it is already July and this is still not resolved. I would have thought you get better customer service with a company such as Discovery. Not certain how else to resolve but report this to the FSB as surely it is ********** to create a new account without the account holders consent.