Cannot trust Discovery bank - and cannot get rid of them! Patheric business morals

Professing to be world standard rings hollow with this bank. I was issues a credit card which i stated i want to only use when travelling overseas. I was told it is fine and costs will be below R100 pm. Lo and behold I was billed after 2 months - without using the card at all - for over R500. I requested to stop the card as the fees they quoted and what they were charging ( you are forced to take out some insurance whic was not disclosed at all) so i stopped it. Their *********** recovery team called to try and entice me to keep the card. i made it clear to stop it. There were some credits on the card which they said they will convert into cash and that there is a positive balance. The next thing 2 months later i get an invoice to pay them over R100. When quering this I was told that the fees have been deducted monthly. The card was not stopped. I queried this and was told they will refund me. Next day i get an invoice for R215. How can I have a settlement amount. I send notice that it was closed and they still paid over credits which showed a positive balance for more than R300. I spoke to an agent who confirmed that the account should have been closed and that the bank carried on deducting fees instead of paying it back to me.