Fed up of this bad service

I was approved for an mobile contract with this supplier - where I accepted and the activation fee was deducted from my accountR199 - I HAVE EVEN SENT PROOF. now my contract was cancelled and they claim I did not pay - I have communicated more then once to Owen the consultant via WhatsApp and phoned him numerous times with no feedback - always promise to get back to me and up to today this promise falls on deaf ears. I'm fed up of the bad service by far.