Isn't "I'm sorry" the very first thing he says after "Hi Anthony"? And as if that wasn't enough, he goes on to say "Our apologies" later in the paragraph.
He said he was sorry that you feel we did x. So he is apologizing for for the fact that Anthony feels a certain way, not the same as saying "I am sorry.".
He has nothing to apologize for. You use features clearly marked 'unsupported,' you are going to get burned.
I was also planning on using twilio for a project and when looking at their faq for the initial research, it wasn't very clear that it was something completely unsupported that could be disabled at any moments...
This is why programmers make horrible customer support people, it doesn't matter if you have nothing to apologize for. You say your sorry because no matter what the circumstances the person is unhappy with your service and your company - saying your sorry and fixing the problem keeps a customer. Sticking to your guns and saying you have nothing to apologize for just loses you a customer.
the features were not clearly marked as unsopprted. there were even price quotes for international SMS.