Challenges in cancellation of the contract. Bad customer Service al99lp

I am not able to cancel the contract because the cellc stores referred me to the call centre for cancellation. The call centre agents informed me that the Security information I provided doesn't match with the captured information. I was advised to go to the store for the identity verification, on arrival a very unprofessional sales person said he couldn't help me, even after I presented my ID card to verify my identity. How do I cancel the contract that ended in November!!! All I am experiencing now is Rude, unprofessional call centre agents and salespersons who don't care about assisting the client. For two years , money was debited from my account. But now I am told my identity cannot be verified, therefore I cannot cancel the contract!!!! The store I visited is cellc Bayside mall in Cape Town.