Ethics discussion: IT dept working on employees home computers/networks

I have a unique question that I haven't been able to find much (if any) information on.
Lets say the IT dept (ContractorA) of said company (Company A) is contracted out, and Company A has a flexible telecommuting policy that allows it's own staff (Company A's staff, NOT Contractor A) to work from home at their own discretion (pending administrative approval) of course.

Now, Contractor A is receiving regular phone calls from telecommuting staff of Company A reporting issues that vary in nature from printers not printing, to wireless networks not working, to files being misplaced deleted, to any number of other issues. Some of these issues are "work related", maybe an issue w/ terminal services, or exchange maintenance....yet some of them are clearly related to the home users network, and/or are self inflicted on a home PC.

So my question/s become:

1. Where does Contractor A draw the "help-desk" line? Meaning, when should Contractor A tell Company A staff, "I'm sorry, but that issue is on your network." It's sometimes very difficult to tell where the problem lies to begin with, so some tech support is always necessary just to determine the nature/responsible party of the problem.

2. What sort of protection does Contractor A have when helping users resolve "telecommuting" issues? What if a techie provides instruction that causes the BSOD or hardware failure? Is it up to Contractor A (More specifically the contractor providing the tech support) to pay for and repair any damages, or is it an at-will engagement?

I know that  a good telecommuting policy/procedure should cover these types of things, but I wanted some insight as to what others companies/contractors are doing in regards to the insanity AKA telecommuting. Any other interesting points or discussion is welcome.

Thanks in advance.
Ap.