Poor service

Edgars is giving very poor service regarding my credit that needs to be allocated. I phoned them in March and sent them the proof of payment and the relevant documents as requested but up until today no credit has been allocated on my account. Instead I've been charged interest on my account every month and interest on my insurance. I have a 6 month account and pay 17% interest which is ridiculous. I phoned them several times, sometimes the calls weren't even answered after holding for 10 min in a queue. They speak to you for half an hour and still nothing gets sorted. I im fed up with this poor service I get. RSC is giving Edgar's a bad name. ?????