Based solely on the limited facts presented in your post, it is my belief that you could have two liable parties. If the tow truck was towing on request of a private party (shopping center, etc) then the private party AND their agent could be liable.
If the tow truck was a public tow (police authorized, etc), then the tow truck only would be liable (I know, the police, etc. could be liable, but the ordeal of including them is seldom worth the effort).
Send the liable parties a 'demand' letter (Certified RRR). Detail the circumstance of the tow (the fact that created the tow is not relevant, only that the tow caused damage). Include your repair estimate and give them a reasonable (5 days from receipt?) response time. If they do not respond to your satisfaction, you will need to consider taking action against them (Small Claim?).
