Telkom phoned me and sold me a product that has no coverage in our area, now refuse to refund me

In June a telkom operator phoned me and offered me 5 gig data contract. She checked on my street address to make sure that I had coverage and she said we have excellent coverage. On top of the contract I also had a R500 available spend should I exceed my data. I was not worried about that because I have never used 5 gigs of data in a month. June and July the product worked. In July I phoned telkom to ask why they have not deducted the subscription from my account yet. They told me that they will deduct it end of the month. My bill was R798.00. I told the operator that could not be. I immediately removed the R500 available spend limit. End of Aug they deducted R645.00 from my account. I phoned on the 4th of Aug and a lady from the technical department phoned me on 28th of Aug. She immediately realised that because I removed the available spend the product did not work as it has no coverage in my area. She said I will be eligible for a refund since this product was sold erroneously to myself. Since then I have been trying to cancel this product and get a refund of all the money I paid, since I only used the available spend limit BECAUSE Telkom had no coverage. Not because I exceeded the 5 gig of data I received. Today they deducted the subscription again indicating that the product has still not been cancelled. I phoned today to report this again and again I was assured that a case will be logged. Case nr ********** 0 and ********** 9. Every time I phoned telkom the calls took between 15 and 20 minutes. That is airtime I had to pay for. I am so disapointed with the service. Antoinette