HELP NEEDED ???!!! PATHETIC SERVICE

Okay,, so I have a laptop contract with this pathetic place. I took the contract out about 6months ago and then went in store to log a case when I came to know that im only getting 1gig data a month. I took the deal where you get 10gig day and 10gig night - and I have been paying for this deal for 6months now - my bill is R560, but I am getting 1gig day and 1gig night - this deal is about r350.

SO I HAVE BEEN PAYING FOR A DEAL THAT I DONT EVEN HAVE FOR 6 MONTHS NOW!!!

I have been going into their walk-in shops every week since i took out the contract but nothing is coming from this case so clearly they dont have any intention to credit me for the months I have been paying too much or to rectifying the deal.

What can I do about this???

someone please help??