Cell C not allocated payments

For months now (since July) we have been struggling with Cell C to allocate our payments on their system. Every month we ( my wife and I) receive messages and mails stating that our accounts are in arrears. We have been paying every month in time. We have sent the proof of payments numerous times to Cell C to be allocated, we even receive mails back stating that it has been done, then a few days after that we receive messages again stating our accounts is in arrears. There is something seriously wrong with their system or someone is not doing their work. I won't recommend Cell C to anyone.