contract ended 2014, money still debited

i took a contract with cell c in game ballito 3 years ago. The 24 month contract was paid for and ended in 2014. in July 2015 money was debited for absolutely nothing, when i called the call centre they told me it was simply a misunderstanding and it was cleared up my money was put back into my account. then again in november 2015 almost R900.00 got debited again. when i called up the call centre the told me i need to contact the legal department because my account was in order and the do not know why money was debited again. after many tries to contact someone from management and the legal department i had no response. up till today (15/04/2016) cell c still did not refund my money. they have tried to avoid my emails and calls. they are such a big company how can they let the same mistake happen twice. Absoluely madness. i still have not received my R900.00 AND THE LEGAL DEPARTMENT DID NOT CALL ME BACK. I had gone to the store in Ballito and the staff told me i need to call up the manager. i have tried to call up the manager on numerous times with no response. Cell c needs to pay back my money ASAP or legal action for theft will be taken.