I'll agree with SargeW but I think most road service providers deal with the same set of local road service companies (towing, tires, etc). Even if they don't have a formal agreement with them, they may contact them as an alternate.
No matter what dispatching service you contract with, they are all at the mercy of the local providers wherever you happen to be when a breakdown occurs. You will see "horror stories" about them all. Some areas have very few providers and maybe not very competent either. Other areas are extremely busy and there will likely be delays at peak times, sometimes hours. Another common complaint is high fees for extra services or purchases, e.g. a tire brought to the site. The service dispatching company has no control over that. Besides, you can hardly expect to get discount pricing when you are stranded on the side of the road on Sunday night!