Misled by Mondo - Mtn Contract

I took out a mtn cell phone contract via Mondo towards the end of the September 2020. The agreed package was 50gig anytime and 30gig night data (Sim only) for R299-00 per month. My Simcard was delivered on the 30 September 2020 and the Simcard was only activated on the 5thOctober 2020. I was so much disappointed when I register on mtn app to see that my pro-rata data was only 19 gig and that and amount of R698-30 was due end of October 2020. I phoned Mondo on *** several times the phone just ring. I am very upset Mondo who misled me taking out the about contract. I sent emails to both mtn and Mondo to cancel my contract with immediate effect and explain the cost of R698-30. A total ripp off.