My security camera was faulty for 3 months before my service provider could get it fixed. During that time my truck was broken into. Are they liable?

Probably not.  First of all, if you look at your contract I'm pretty sure that you will find a clause limiting the service provider's liability to some nominal sum.  Alabama law may be different, but in NY such clauses are emfprceable unless you can show that the the service provider was grossly negligent or reckless, in other words more than just negligent, and that such negligence caused your loss, i.e. that your truck would not have been broken into and/or that you would have recovered your stolen goods if the camera had been working.  Those are difficult propositions to prove. Also, did you know that the camera wasn't working?  If so, the service provider will argue that you could mitigated your damages by taking other precautions.  For example, had you leased another security camera until the first was fixed and then tried to recover the cost of the extra camera from the service provider, I thnk you would have had a better claim (Of course, if the reason you didn't do so is because the service provider kept promising to have the camera back to you in a couple of days, you would have a good reason not to have replaced the disabled camera).