Cellc worst service provider when it comes to contract

Took out a cellc contract for cellphones +_ 3 years back. I paid 3-4 instalments and decided to settle the account and cancel the contract at Cellc riverside shop.

Upon arrival at the shop I was told to go make a payment at the ATM, given cellc accounts and I did. Brough back the proof of payment , they made me call the center for cancellation in the shop which later they said it was successful.

I’m currently frustrated because I now have a third party saying I’m owing cellc cancellation money which was not disclosed on the day I cancelled . Now when I call cellc center to ask for a paid up letter and contracts all of them their system is not working. Been on the call for 2 hours no help. Every month they try to deduct on my bank account. Worst service provider