I was overbilled on my recent cell phone statement

On 21st December 2015, I have requested my recent statement from Autopage and I still did not receive it. When I logged onto their website, I have realized that I have been overbilled by approximately R1700.00. When I queried this, I was told that it was a mistake and it will be rectified. On 23rd December, I have received a sms stating that I must make an immediate payment in order to prevent my account being suspended. On 24th December, my line was suspended. They people in accounts were so rude and unhelpful. I have this contract for almost 15 years and all the invoices were paid on time. My line was re activated again on 24th December. On 29th December, the line was suspended again. I drove 110 km's to their offices in Midrand was treated very unprofessional. Whenever, I have asked to speak to a senior person, I was just told that they cannot see me. The service received from Autopage is really unacceptable and would like the MD to contact me in this regards. I was unable to liaise with my clients and got into trouble at work for Autopage's mistake. I expect proper compensation for their poor service.