Poor service and non assistance from Telkom

I have a data account with Telkom. Tree years ago I had an additional spend limit of R500 in case I ran out of data, which I cancelled three years ago and not once since then was I debited for it. A couple of times my data was depleted and I did not top up and waited until the end of the month for the new data to be made available. However these past two months round the 15th of the month my data were depleted, where in the past it would perhaps happened round the 27th of the month. For the remainder of the month of August every time I got home my cellphone tried automatically to connect and the message "no access, data depleted" with options to top up appeared on the screen. I simply left it and did not bother, until I got an account indicating that the R500 spend limit now all of sudden has been reactivated, by who? Telkom cannot assist as they claim do not have the infrastructure nor the resources to see who accessed my account and reactivated. The full amount of R500 worth of data was utilized on 18 August at 24:00 in big amounts of mega bites. Telkom just refuse to assiost and says I have to pay these amounts as their account shows it was my router that used it, they do not even listen , nor try to assist. I will not pay these amounts, until such time I have answers from Telkom.