These scammers impersonate airlines such as United: - YouTube and actually have their own website with a dedicated suppoat line: http://www.skyflytrips.com/
Their numbers:
(800) 348-5370 (impersonating united airlines reservations)
Now, I can't list their 513 number that's on their own site, because it appears to be a TMobile number.
But, it looks to be the number of one of their call center agents.
Call away!