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.
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.
Edit: this was ~13 months ago.
Google and Paypal were the ones who started it in our industry, of course, but it certainly seems to be spreading.