Telkom is by far the WORST cellphone provider

My device and phone were blocked due to non-payment. My account was handed over to VVM Debt Collecters (also have the worst system). I made a full payment on 2 February 2015 and they have been taking me from pillar to post. They cannot unblacklist my phone and are practically forcing me to re-instate my number. I have made it clear to them that I no longer want the number, I just want the device to work since I have paid for it in full. I have also requested a letter saying the account is paid in full and they are struggling to provide me with the letter. There are just too many loopholes and it's actually quite disgusting that they can never get anything right.