False advertising

On Saturday I went into MTN, Mall of Africa to sign up for a Sim only data contract which is advertised in TWO current catalogues. After more than an hour, I was told that they could not find the advertised package (100GB anytime data and 30GB night express for R349.00 over 24 months) We contacted customer care on Monday and today, Thursday, have not had a response. We are looking at changing from another network to MTN - two contracts. Is this a huge mistake?????