Paying for a service i cannot use

I have a Iburst 10GB wireless account and was getting speeds between 0.7mbps and 0.8mbps, which was ok as the modem was a 1mbps wifi modem, I moved to a new area and on the coverage map on the website it is the same as my previous address but now my speeds are 0.01mbps the best was 0.02mbps. when i speak to the technical department i get told the only solution is to put up a booster antenna, the retentions department tells me that the speeds i was getting at my previous house was due to \RF bounce back"in other words a fluke and the speeds i am getting now are the speeds i should be getting even though the coverage on their map is identical. I work in the RF telecommunications industry and have never heard of bounce back. I got tied into a contract where nothing was mentioned about \""bounce back\"" now i cannot even open an email the internet is so slow and to make things worse to cancel the contract i need to pay R1600 and return the modem. Personally i think iburst is a company that ****s people into contracts with false coverage maps and when someone wants to get out they need to pay the cancellation fee which is the goal all along NEVER to provide a service"""