Shipping Haz Mat to the WPC

Can anybody help me with the procedure for shipping a Haz Mat part to the WPC? I tried this last year and ended up being billed like $600 that I later had to get a credit from GM for...When you try to print the shipping label in Global Connect they give you a phone # for UPS and when you call it they ask you for your account # and or shipping #! Obviously we do not have that information since it is supposed to be billed to GM. I am Haz Mat certified so I should be able to ship this myself...Does anybody know how to get a shipping label for a Haz Mat item?
Thanks in advance for your help.
Thanks in advance for your help.