Its hard to justify in words what we feel when our most beloved possession (and in this case as guitarists) our voices, to some extent are lost for unpredictable amounts of time, or the amount of stress/worry/anger at mostly imagined negative outcomes during the time when its all up in the air.
Hopefully now (staying with the up in the air analogy) this is getting near the bit where you can tell where and roughly when the ball is gonna land.
Just hang on in there. The sadness is inevitable and if you've not killed anyone, then you'll have done well. This is the week, I believe, where you overtake me in my length of time it took to get sorted, so I'd be stunned if you dont hear something concrete this week.
I hear you on the point you made before about not raising so much of a fuss that it could somehow affect the repair process of your amp.... its a situation where teeth gritting is essential. But surely better now the company are aware... Once Mesa gets on to those distributors, hopefully that'll be all thats enough to sort your amp out either by guidance of the techs in your country, or by some kind of priority dispatched replacement or something....cause they can't let this go on forever....I bet they wouldn't be too happy if loads of european based consumers are left with non-working amps and with their d!cks in the wind on account of lazy/unprepared outsourced repair guys.
If it turns out in the end that you were being messed about by the store, then I'd definitely give 'em all the negative publicity that they'd deserve, but I'd certainly make sure that that was the case first, of course.