I got an email from them today as well, that they are removing the above mentioned countries from the international call boost. This is very sad and wrong. I switched to talktalk recently only because of these calls.
That was probably their intention to lure customers from other providers with such an attractive offer. I wonder if one can argue and get out of contract without a penalty. I was already with TalkTalk so it's not going to bother my much but I'll be giving them an earful if I was you. It would be interesting to see what third T&C's say.