Towing Issues: buisness towing threat, tow truck driver, parallel parking

Question
I live in Alabama and am attending UAB.  I parked on a street across from my apartment in a parallel parking spot in front of a business. The business put a computer printed note on my car threatening to tow me because they needed the spaces (there are always extras even with people from my apartment parking there and there is a parking lot around the side of the building).  

They have no sign saying the space is for customers only and since it is on a public street I wanted to know if they have the legal right to have me towed? (If they had not threatened me i probably would have moved for them.)

Answer
While it sounds like a great threat, A private business does not have the legal rights to order tows from public streets...
Lots of people think they can have vehicles towed from streets, but the police are the only ones that can have it towed Legally...

YES they can call the police and complain, but that would most likely result in parking tickets.

Now I have to ask, is there a parking lot for tenants of the apartment you live in?   If so, are you using the street parking because it's more convenient ?

I hope this answers your question, but as I am not a legal expert, I just am a tow truck driver in Lower Bama ..