Blatant Theft on Account

Where do I even begin. The continued billing for a cancelled contract. It was eventually cancelled and agreed that R2500 odd would be put down as credit, since we were billed for a service no longer existing. Fast forward to now, and not only has that credit mysteriously been forgotten about, but the account has been debited twice in one week. This has not reflected on our account and our services are still suspended, with a R2000 debt!!!! This is blatant theft. And it is impossible to get a hold of anyone at all about this.