Impossible to resolve bad debt queries

This Vodacom account was initially in my name. In 2003 I was leaving the country and my sister needed a phone, so we agreed that she'd take it over. She transferred the account to her business. This business she sold 2 years later. Whenever she wanted to transfer this account into her name Vodacom insisted that I be present and sign, so this never got done. This all happened in Pretoria.<br> <br> In April 2013 we both went to Herm**** Vodacom to convert this account to a pay-as-you-go. Vodacom quoted a final amount payable, which she paid on that same day. Two months down the line Vodacom started sending sms's demanding payment of arrears on this pay-as-you-go number. She disagreed, and after a few visits to the shop without any success, she just resolved to ignore the threats.<br> <br> In July 2015 I went to Herm**** Vodacom wanting to take out a new cellphone contract. My application was declined because of the above account - which I have no connection with save for the fact that back in 2002 the account was in my name. All my efforts to solve this mess even though it is not mine, has been unsuccessful.