Herotel wifi..bad service

HX Systems changed to Herotel, we are in a area that we pay R699 for a 6 mb line but its very bad service.we get if we are lucky during the 5mb speaad and after 5p from 1mb to 2mb. We have phoned them numerous times and they check and its fine for a while then its all bad again. One of theyre guys came to our home and said the wifi signal needs to be moved to a different location on the roof and we have to pay a once off fee.?! Its ridiculous as we have been paying for a service that does not render the service its suppose to provide us.Our area dont have fiber yet and one has to make use of wifi providers