997 GT2 Tyre Rub - I need a detective!

[am0611]

Here's an interesting (and very annoying & expensive) puzzle that needs solving!

Story
1) 997 GT2 currently at 34k km, owned since 4k
2) November 2012 - At 26k km had all four tyres changed and alignment redone - not at Porsche dealer (actually trust the guys who did it more)
3) June 2013 - Re-registered which involves tyre inspection and no damage seen
4) September 2013 - At 32.5k Major service done at Porsche dealership here in Dubai. This includes tyre inspection and no damage seen. But did not include any wheel alignment or similar changes.
5) Only driven 1,500km and noticed rubbing damage on all 4 tyres. May of happened earlier but I park in badly lit basement so would not have noticed.

To me the only thing that could have caused this on all 4 tyres is something Porsche dealership did during the service.

6) Been to see dealership and they are saying (of course) problem caused by non standard suspension settings and poor fitting by non-Porsche people.
7) Note - The suspension setting are non standard due to previous owner using car on track but his has not been changed for 30k km

Can anyone tell me something that is part of standard Major Service that may of changed the fitting of all 4 tyres in relation to arches that has caused the damage. I know wheels were removed during service to inspect the brakes.

Help please...