No because they also called Vienna and Madrid ;) Apparently the Vienna Mayor didn't notice a thing and even sent out a tweet afterwards. The other two at least got suspicious when the supposed Klitschko asked them weird questions.
It's interesting that they ignored that whoever pretended to be Klitschko did not speak in German with them.
But I guess this is how it works, when you already trust the other person, you ignore this stuff and invent plausible explanations.