Calipers are either free moving or they arn't, your calipers might come round with correct lubing of the piston and working the piston in and out a few times, that would be my first action including checking the sliders are free if they are of a slide design, but i would have done this at the time the pads/discs were changed, and your mechanic may well have done so too and his suggestion the calipers are past it is probably correct, and Hardway is quite right about alloy calipers, they almost never last like cast steel.

The poster above is quite right about too in tryng your best not to leave the brakes applied following a very hard stop, material does transfer and the pads holding tight don't help the disc cool evenly.

There is another possibility too, are the rear brakes effective enough, it wouldn't be the first time that front brakes were doing more than their fair share, being overworked and overheated leading to warping, it was possible to judge things like this before the days of ABS, because you might have front brakes prone to locking too easily, with ABS doing it's thing it's not so easy to tell.

These brake problems are all exacerbated due to brakes not being serviced correctly, almost no mass produce maker has proper brake servicing in its service itinery, Toyota used to, every major service (so every other year or roughly 20k miles) the brakes were strip clean and lube (and yes they did it too), i don't know if this is still the case, i've done this for years too and if you keep them clean and lubed the hardware last forever...for too many garages a brake service comprises peering at the things and squirting brake cleaner about, no wonder they seize.

May is suggest if you do need new friction materials again to go for Brembo, i've been very impressed since changing to these, last time i looked ECP/carparts4less offered Brembo at decent prices.

edit, it might be worth checking the Jag forums to see if the XF has a habit or warping/eating discs, long time ago but i bought an ex police driving school Rover 800, that thing got through many sets of discs and pads in the hands of the old bill and it continued in my ownership, they simply weren't up to the considerable performance of the car...i suspect the equivalent Honda Legend didn't have this issue.

Edited by gordonbennet on 13/02/2018 at 18:34