fcb, got to be a good sign that they contacted the cc co. though it would have been nice to have contacted you also.
If the warrenty was included in the price, and something should go wrong with the pc (should you get it back, hope you do) and savastore won't/can't honour it, then you can claim off your credit card Co. to get it fixed/replaced as they are jointly responsible.
Goog luck, and let us know if savastore return the pc