I once had cause to attempt to seek help from Facebook on an issue we were having building something for senior Congressional leadership. They blew us off when we had leader's aides calling and asking for help. It boggles my mind how hostile FB is to people working with their platform.
The general consensus is that phone calls are for super urgent problems (server is down!) and/or paid phone support. Did your contract include paid phone support? I wonder how you would have been treated had you sent emails.
I believe that at one point they had leadership staff members literally going over to the office of FB's guy on the hill. Unfortunately I have no idea about the contracts, but given the cast of characters involved, I'd have thought it wouldn't have made a difference.
It was among the most appalling acts of customer service I've seen from a vendor in my career. They literally did not return our calls or emails and the project ended up cancelled.
What disappoints me, really, is the attitude that's made its way over from other fields into tech: once you're at a certain scale, it is acceptable to provide no customer service whatsoever, even to paying customers.
Google and Paypal were the ones who started it in our industry, of course, but it certainly seems to be spreading.