Pathetic customer care

After having a 6 months interest free account with Edgars for 15 years, they suddenly decided to change my account to 17,5% interest account without me signing OR agreeing to this. I have tried resolving this issue for 3 months now but the customer service is non existing. The accounts department does not know what is going on and blames the system. So I think it is time to stop shopping at Edgars