Please cancel this new contract and revert to my old contract

I have a 25Gig contract which comes with (25Gig + 25Gigs). So its 25 Gigs but comes with free 25 gigs. My data finished 2 days ago and I upgraded it to 50Gig 2 days ago. I was then charged R97 pro rata to complete the month and I paid the R97. However no pro rata data has been allocated to my account because my usage data already shows that I used 50Gigs on the old 25Gigs. None of the 5 consultants has the intelligence to realise that the old 25Gigs comes with its own free 25 gigs. So if I am upgrading the old contract falls away and a new contract is birthed which should come with its own 50Gigs pro rata. Now I have asked all the consultants how was I able to use 50Gigs if I am only on a 25 Gigs contract. When I ask that question the phone conversation gets closed and I am told someone else will call me. No has called. This is all confusing for you can you please just cancel the new contract and let me continue with my old 25Gig+25Gig. Remember there is a cooling off period if a client does not like a new contract. So I am still within my cooling off period just cancel the new contract and let me continue on my old contract Thank you.