Upgrade turned to a new sale

Good day

Please help me with telkom, I upgraded my Telkom contract in October and in November they debited from my bank the correct amount of money but in December they debited a R1146 which is not the agreed amount and I called them today and I am told my bill is R2553 and that my contract is uncapped of which I didn’t agree to, all along I thought I am using data and airtime that I buy as an add on.

The consultant I spoke with today told me that they made a new contract instead of upgrading my old contract.

Please assist