Hidden/unfair charges

I got a new contract on 22 July 2017 with Telkom Mobile. A Samsung S8 on a FreeMe 1GB contract for R629 pm x 24. What was advertised is: the phone, a convertible wireless charger, 100 FREE all-network minutes pm x 24, FREE 10GB for 3 months and the standard FreeMe 1GB contractual benefits. The 100 minutes pm is the reason I signed up for this particular deal. My previous contract was a SmartPlan 100. I get a statement with an amount of R 1,784.32 payable. I have to pay outstanding device fees for the previous contract. The case number for this is ********** 7. I am told that because I "migrated" to another package, they are charging me the outstanding balance of the old contract. I was eligible for an upgrade and this was the idea with the new contract. The thing is, my old contract is no longer an option, as Telkom cancelled these contracts and they are no longer available. You can only choose the FreeMe contracts as postpaid.