Local antitrust agency recently told that they will look into this "synchronized pricing rise". However I really doubt that they will do anything about it.
Vodafone and O2 got fined with 20M last October for price fixing and that's not the first such fine either.
don't think they can. Telcos are not going to say "we raise the price because roaming" so, even if we all know, they will walk away.
I'm sure their lawyers made sure they could do it... sadly.