Airtime billing on my account which I dont receive

I have been calling, emailing for the last year or so and complaining about my account being billed for airtime that I do not receive. Despite my enquiries about this there has been no response and instead my account has continued to be billed! I pay my account on a monthly basis despite this. The call centre informed me of the number this airtime has been sent to and it is not even my cell phone number. So I have been billed on my account for someone else's airtime? Totally unacceptable. Its enough this has to stop now otherwise I will stop payments on my account until this matter has been resolved. I need an immediate solution to this.