Jet/Edcon bad customer service

Hi, I have an account with Jet/Edcon that I can’t use. I have visited the nearest store and tried to call customer service with no joy. Now I want to close my account since I can’t use it,Still no one can help me. This is really frustrating coz I don’t owe them anything,in fact I’m ahead with my payment. I took this account for my child but what’s the use of having a card that doesn’t work.instead they tell me they can see I have credit but they have no idea why I can’t use my card. I have waited over 500 trying to call customer service and I went to different Jet/edgars stores but no one help me.This will affect my credit record and I need it sorted out ASAP