day light *******, Cancel my contract and refund me

I would like to express my disappointment and frustration with cellc, for over 10 years have I been a cellc customer currently still have an active contract for my wifes device, my disappointment started in early October cellc contacted me for an upgrade as they realised my contract was up they also offered me the option to use the data and minutes in the current simcard at the time without upgrading, I have then advised them that due to fincial difficulties I do not want to upgrade Nor keep the simcard and would like to cancel, the consultant at the time then advised the that the contract has been cancelled, at the end of October I realized that the debit order for a slightly higher amount was then still going off, then I called them again, they advised me that it will not go off in November and will be cancelled, however this was not the case, as the debit order continued to go off until January whereby I was very upset and irritated and decided to stop and reverse the debit order with my bank, it is now end of FEB and cellc decides to change the reference and debit a whole R648 from my account, after i have clearly stated many times i want to cancel the contract as my 24 months is complete, they refuse to cancel and continue to debit me which is against the LAW it is unauthorized as i cannot afford it