INCORRECT INFORMATION GIVEN ON CONTRACT

I was called by EC3 to renew my cell phone contract. They could not match an offer I got from MTN DIRECT. I called back and asked them if this would be possible , the supervisor assisted and explained to me how the MTN Direct contract worked (sky unlimited with uncapped data) .They convinced me that to take the contract even though it was the same but with only 10gigs Data. the contract was concluded on the 19th March 2015 and my phone was to be sent with 7 working days. a few days later i get called wit cell phone contract offer from the same company,I inform them that I just concluded a sale a few days prior. On investigation they see that i have concluded a contract, but the DATA package was only 5gigs which was not the agreement. they disputed this bt on listening to the recording they agree d that i was correct and that they made a mistake. Although they admitted this they would not honour the contract as agreed. I gave them numerous opportunities to rectify the situation but they would not budge. I asked if i could get a copy of the recording and was told that that is not allowed and i had no right to the recordings. I then said that i would take it up with the OMbudsman