Poor service

I requested a settlement quote for the contract I have with MTN which their social media account was able to provide me with. This was after I called and emailed their retentions department with no success. After I paid the quoted amount, I sent through the proof of payment and I am still waiting for confirmation that the contract has been cancelled or some form of acknowledgement, but I have received none. I want to cancel my contract and I have paid all the balance outstanding.