Clean credit record but Telkom refused to give me a R199/month data contract

I went to Telkom at Springs to apply for 15GB Wi-Fi contract which was going for R199/month. The sales person(Lerato) tried to apply for contract on my behalf. She says on Telkom system, it says I have an existing contract/account & I have worked for Ambit. I said I have never had a contract with Telkom. I bought a prepaid Telkom Landline around 2009 & I have never worked for Ambit. She also said the system is refusing as it stated that I have defaulted in one payments of mine in the last 6 months. I then told her that I recently checked my credit report & it was in good standing. She advised me to contact Telkom Head Office. Although I have never had a contract with Telkom but it was unfair for Telkom to refuse me a contract whereby I have a good credit standing. Can Telkom explain to me why am I treated like this as a new customer as I need the new contract from Telkom?