$1700 is excessive for TPMS and a flash.. What else did they find that would cost $1000 to fix (400 for sensors, 100 reflash and 2 hours of labor rough estimates)?
I would threaten to bring attorney into this. There is a law that protects consumers from this type of BS. Your warranty is only voided if they can prove that aftermarket modification caused a component failure. Very important, so expect to pay for new sensors, labor, not sure why reflash is needed?? But give them hell, sounds like a bunch of BS there...
2014 F25 X3 M-Sport Carbon Black, Technology/Premium/Winter/Driver Assistance
2011 e92 335is DCT - Cobb, ETS IC, AFE DCI, BMW PS kit, M3 control arms, various cosmetic improvements RETIRED!
2007 X3 RETIRED!
2006 e90 330i 132k miles RETIRED!