I had the same thoughts going through my head, having to change tyres each year is not a good thing, other members have said that you need to take the car to someone with a good eye who can see if there has been any damage to suspension subframe etc not allowing camber/toe to be adjusted correctly to spec, but i got the same story as you: take it to a mechanic who will start changing out part by part ! not correct in my view, and that this may not fix issue! i am even considering swapping my 19" alloys for 17" and hence smaller cheaper tires, if my setup was not staggered i would have been able to rotate and live with doing this but cannot, front wont go on rear vice versa......good luck with yours and you are lucky to be getting it done free of charge, please keep us posted