VERY BAD SERVICE

I had a contract that was expiring and I informed Cell C that I do t want to renew. The Retention department processed my request as per my request. On the 28 May a deduction was made from the account I gave them and told them the previous account is not in use and I have reported Cell C and that was never changed. So, Cell C decided to also debited the same account not in use hence on the other hand a deduction of what was said will be deducted to close the contract happened. I called Cell C customer care trying to understand why I have balance if deduction of what I owed was deducted on the 28 May and now that amount deducted from account not working came back as unsuccessfully and charges were added there. They told me I have to pass security check and they asked me questions which were about me and which I knew answers for them..like my id and my names, but funny enough the agent told me I didn’t pass security check and she couldn’t either explain.