Extremely poor service

Tech5 is the worst internet service provider. I am paying for 200mb download , but only getting less than 100mb download. I have sent numerous mails to them asking them to get the line checked, but all they do, is ask for the result of a speed test to be sent to them. I have done numerous speed tests and sent the results, but they just don't give a damn, so long as they getting payment via debit order at the end of the month, they not bothered. To me this is *****/theft whatever you want to call it. This is my last resort. I need help to get through these dumb idiots.