Telkom *****ing my money

How do you explain this? Telkom has been charging me for a sim card that I have never had. Since 2018! I have been working for them for years trying to rectify this. Now I have been told I have to pay R2123.00 cancellation fee for something I have never had. Apparently they will refund it, yes sure when they already owe me approximately R6500. What a ****!!!!!