There are towing companies that operate like this as well. Their rates also tend to be on the ripoff end of the spectrum. What these referral companies tend to be very good at is search engine optimization, and taking advantage of people in a bind. If it's a plumber, towing company, electrician, duct cleaner, handyman, kitchen or bathroom reno company, or even escort
try to find a good, well established, local provider or company, not just the first thing that pops up on search (fake reviews and all), or that flyer in the mail (if you're old).
@Josephine, that's a terrible experience. You certainly weren't given a friendly, "quick fix", rate, and were ripped off for the service provided. Having a guy refuse to leave without money is outright intimidating (and, I'd imagine quite scary for many women). At that point I would seriously consider dialing 911, and using words like single woman, man refusing to leave without money, and feeling threatened. That may get TPS to move. Offer to pay what you think is a fair price, and invite them to take you to small claims court. Though I get why calling the cops, or "big drama", may not be your go to move...
Without putting any blame on you, for any sort of work on a home or vehicle always demand a reproducible quote up front (if not a written estimate at least a text or email), and always insist that you need to authorize any additional work. Most companies will do this without asking (as they don't want drama or to go to court), if not, insist.
It sucks that you were ripped off and intimidated. The best thing to do is just to move on. A service was provided and money was exchanged. At that point getting any redress is hard.
One thing you might want to do is keep a can of compressed air drain clog remover. "One Second Plumber", is a big brand there. Plug any secondary drains or overflow drains (a rag and pressure will do fine), and give the clogged drain / toilet a short blast of air. It's generally safe and effective, but if you're plumbing is coming apart that might finish it off. If you want to "double tap" the problem drain you can hit it with some drain cleaner afterwards. Many people find that less intimidating than trying to use a snake.
I'm sorry for your experience.