Franz is correct in his post. Ask to keep the old angle gear and also get a write up of what failed. A Volvo regional representative should be called by the dealer to explain why the angle gear would fail with only 125,000Km (78,000miles). My dealer would be put on the spot if it were my car.
Of course, your tires are matching aren't they? You know that you cannot just buy 2 new tires for the front and be happy, you must have all 4 of the same make and size and tread pattern. If not, it is your fault for the failure.
When you get a new angle gear, remember, the spare tire can never be used even for 10Km. Rotate the tires every other oil change, front to back.
Let us know the outcome with the dealer. It is an expensive car, there should not be expensive repairs.

Klaus
--
1975 164 w/174,800mi (Sold) 1995 850T w/91,000mi, 1998 V70R w/129,000mi