ACER Stealing, neglegent , Internet

We have a non-profit educational foundation. We have set up a classroom for students to learn all government day to day functions of the Oval Office. We have 15 Acer Computers. I had five LCD monitors go bad, i.e. screens would just stay black. At the time the monitors were registerd and under warranty, so Acer authorized the repair and I sent them back to them. Upon receiving them back from Acer, I noticed that none of the bases were sent back. So I emailed them with regards to this, and they bluntly told me that they do not have them, and that I would have to go through a distibutor and purchase them. I told them, why should I have to purchase them when they were originally purchased withy the bases? I told them this is un-acceptable, but have not heard one word from them. I have documented emails and incident numbers as well