Charged incorrectly

My experience with Wonga has been incredibly frustrating and disappointing. Despite having paid my account in full and on time, I've been consistently told that I have an outstanding amount. To make matters worse, they've even charged me a penalty fee for this erroneous outstanding balance. I've reached out to their customer support numerous times, and while they keep apologizing for the inconvenience, they've failed to resolve this matter for over a month now. This level of inefficiency and lack of accountability is completely unacceptable. Wonga's inability to rectify this issue has left me deeply dissatisfied and I strongly advise caution when dealing with them.