MTN stole my money

Hi I got a call from Mondo in mid January 2021, the consultant was offering me a 30 gigs for r150. I took package because to me it was a great offer indeed. But when I received the package there were two simcards, on the same day I took the simcards to MTN at Somerset mall to send them back and also sent an cancelation email to Mondo. To make the long story short the package is not canceled yet, MTN is still debiting the money from my account for the wrong package which is r540 instead of r150 even when I phone *** ask for cancelation it rings forever wow