Incorrect billing amount and refund required

Good day

I'm really disappointed with Telkom and their service, i had a Data contract which expired around end of October

I was then contacted by a consultant who offered me an up grade in November which was going to be effective from 1st December for 40gigs : 20 gig day and 20 gigs night at the price of R199 which i felt was affordable and i went for the option. On the 20th of January an amount of R499 was debited from my account and till this day i have been sent from pillar to post in order to rectify this matter as this was not the agreed amount and no invoice as been received with the break down of all these costs.

please assist with processing an urgent refund for the amount and assist with the correct billing amount.