Do you have a separate modem (probably not called that, but a device that "translates" between the fiber and ethernet) to which the router connects? If so, connect a computer directly to the modem and see what download speed you get.
I am almost positive, from what you've described, that there is a serious problem with the service or with that "modem" and you will not be able to do anything except hound them to get on it.
I am almost positive, from what you've described, that there is a serious problem with the service or with that "modem" and you will not be able to do anything except hound them to get on it.