They cancelled my account and returned the device yet still bill me

I previously wrote about the bad service received from cell c that caused me to cancel my contract within the first month. They tried to delay fetching the device. After writing a review they speeded up the process and had the device picked up.

When I call in it's clear the contract is cancelled but this isn't the case on my credit report as well as my debit orders as they continue to debit my account twice every month.

It's really annoying now and I just want to have this matter behind me.