The tow cost for an RV is completely different than the cost to tow a standard passenger vehicle. For example, I need a medium duty wrecker to tow my clipper - the standard rate in my area (on a weekend/holiday) for that truck is about $175/hour.
In the case of the OP, he has had GSRA for 2 years and has had "2 or 3 tows" during that time.
I have learned that the longer you wait to initially use insurance, the better your odds that they won't cancel you. If you use your insurance within the first two years of having it, they will see you as a greater liability. Most people who claim soon after getting insurance are more likely to make regular claims.
That's not to say the OP should have been cancelled, but just an explanation of why companies work that way.