First, attempt to resolve your customer's problem using the Developer Knowledge Base or in the UPS Developer Kit Community. If you're still unable fix the error, email support and a first level Technical Support representative will respond.
If your issue is urgent and you need immediate assistance, you can call the first-level Technical Support desk to:
U.S. - 800-247-9035
Canada - 1 (877) 336-1100
8002479035