Unhappy customer

Ive had this problem now for months just when i thought it was sorted out. I signed a contract with Warda at vangate mall mtn for a 30GB deal per month for R199. Instead i got 40GB for R299. This was going on for months then only after numerous attempts to get it sorted Masnoena at vangate mall MTN sorted it out. NOW im getting 15GB but im still paying the price of 30GB deal. Im fed up! I cant operate like i normally do as far as my business is concerned. Im loosing money, im getting irritated, im not happy with the service. No compensation was even offered, no apology, nothing!