Unfortunately, Thunderbolt Carpet cleaning companies have gotten a negative stigma attached to the industry by conducting an unethical practice known as baiting and switching.
The Baiting Part:
The baiting part consists of getting their foot in the front door by offering you specials that are hardly too good to believe, or promising miracles cleaning performances to carpets that are probably better off replacing. Essentially, they are taking advantage of people who are in desperate predicaments by getting their business by offering amazing rates.
The Switch:
As you may already know, when you take the time to book an appointment, you probably re-arrange your whole calendar so you could be home when a technician arrives. It's fair to say that you are pretty much committed to going with the said company and this is the logic that goes behind the baiters and switchers. They realize that canceling or re-scheduling is not the best option and they figure, "Hey, since we're already here, why don't you just pay the extra fees that we're charging you and just be happy?"
The trick is that once a technician (Or salesperson, you could say) arrives at your home, they start upcharging for every stain they encounter, or add more to the fee because of larger than normal sized rooms. So by the time they finish their walk-through, your price over the phone has sky-rocketed to an outlandish overpriced fee.