If I paid Good Sam ERS by Credit card. I would put a claim in with the credit card company. I would also contact your state insurance commissioner or state attorney general's consumer complaints division. Trailer Life magazine has an ombudsman column that seems to often get positive results from RV vendors. Maybe your local TV station's consumer assistance hotline could help.
I have to add my experiences with Good Sam ERS. I have used them about 6 times in 6 years of RVing, from flat tire/spare swapouts, to a bad tire/cracked drum which required 2 vendors, and a roadside repair. One time while towing my rig in hot weather, the water pump on my truck blew, and GS sent a big rig tow to tow my truck hitched to the Bighorn. So far all of my interactions with GS have been positive, even getting tows 2 times on Sunday afternoons.