Roadside Assistance Towing vs Actual Assistance??

Many tow policies will pay either towing - or - up 1 hr labor at the scene of disablement. As you found out the problem is finding someone who will bring out the part. I think you may have had the right idea with calling an auto parts store and have them deliver the part to you. Cost of part wouldn't be covered, but the cost of delivery in lieu of a tow should be.