As the owner of an 89 Porsche 944T, I can tell you those clips will break as well. They will probably last a bit longer than the Volvo parts, but I've had to replace a pair on the Porsche as well. VW makes a part that is nicer, and bolts right into the 944, so it should bolt right into a 245 as well. It's got a spring loaded bit, so I think it will fatigue the plastic less, plus there's an additional little cover that will clip on to hide the screws, if you care about that sort of thing.

Here are a couple of pics of the VW clip & cover, next to one good and one broken 944 clip:
http://i.imgur.com/j2jHvj1.jpg
http://i.imgur.com/OcqDZu8.jpg

And of course the part numbers, if you want to go out to the VW dealership to buy a set for yourself:
3B0 857 561 BY20 . . . Pearl grey
3B0 857 561 BB41 . . . Black
3B0 857 561 B8YS . . . Light Beige

For the clip-on dress cover:
3B0 857 563 BY20 . . . Pearl grey
3B0 857 563 BB41 . . . Black
3B0 857 563 B8YS . . . Light beige