Make sure that you're contacting the true ISP (don't ever call a phone number on a pop-up )
... I've never heard of any provider requiring that a user take a course
There's usually a way to reset a router to factory defaults (a reset hole, a reset button, or long hold the power button). If your network requirements are simple, then this might be something to think about.
Try going to a site that throws the error and change the URL from HTTPS to HTTP.
That's all that I can think of.