That's crap. Speak to a manager?
When I call my ISP because my internet is not what they say it ahould be, we run a speed test, if I don't get what they say I should get, they mess with something and then I get the speed I should get.
A guy once told me his friend used to work for an ISP, and he had a CD he could just pop into any computer and get the computer to have 100s of mbps back when like less than 20 was standard.
As far as I know, it's generally controllable on their end.
Are you using Wifi, or hard wired? If Wifi, you may have to play with the settings / frequencies, especially if you live in a densely populated area like an apartment. Try hard-wiring if you haven't already to narrow down what the issue is.
All in all, sorry, I'm not too savvy.