Towing Issues: towing a legally parked car, parking stickers, tow companies

Question
I live in an apartment complex in Massachusetts that uses parking stickers to designate legally and illegally parked cars.  I have a sticker and so am a resident in good standing.  The other night I came upon the tow guy in my car and hooking it up to the tow truck.  He said that because it was on the truck he had to tow it.
I find so many things wrong with this, how much of this is legal and if any, how much is illegal?

Answer
More information is required to properly answer the question. First why was the vehicle being towed and what city or county? Most tow companies have a drop fee for illegal parked vehicle once hooked and the owner shows up. If the owner has the appropriate method of payment and proof of owner the tow company releases the vehicle.