said by 34764170:
Reputable is so subjective. Even TSI for a lot of people would be considered fly-by-night too.
said by Guspaz:
TSI isn't fly-by-night by definition, since they've been in business for 14 years...
I think the word(s) you are both looking for are:
disreputable, disgraceful, dishonorable, ignominious, infamous, louche, notorious, opprobrious, shady, shameful, shoddy, shy, unrespectable.
They even use an internet service provider as an example in the link. Very similar to the No refund issues for the low quality (or non-service) we see.
So take you pick of one of those words to describe them.
But fly-by-night works just as well since in infers a company who takes your money and gives you nothing in return... kind of like getting a 2-meg service when you were sold a 30-meg service.
So the definition kinda fits them.