cell contract cancelled ***8A case ***

I took out a cellphone contract on 28/11/13. On 30/11/13 the simcard was inserted and within hours all the data had disappeared. We called customer service and they saw there was a problem but couldn't help us. The next day 01/12/13, same thing happened. We were away on holiday at Dikololo in the Britz area. We spent two days on the phone to customer service and no one could advise us on why the data just disappeared. On Monday 02/12/13 I sent the branch manager at the Telkom branch at River Sqaure Vereeniging where I took the contract out, an email requesting to cancel this contract. She confirmed that there will be no penalties. I have all these e-mails. She also had all the ref numbers for the calls to the customer care dept. The cell was returned 6/12.The phone was switched off when we received a message that all data was depleted. Months later Telkom took a debit order off my account for R430, which I returned. I queried it with Sheldon and he insisted it was data that was used. After all this time I am being hunted down by debt collectors for R1800 by now. I have all the correspondence between myself and the branch manager but it did not seem to make a difference to Sheldon.