W202 front springs broken any thoughts why
 

I have a 98 C280 that has two broken coil springs!!
This came to light when I changed the ball joints which were bad at 55K!
I have never had a spring fail let alone two . This has been serviced by the dealer who when he told me about the balljoints didn't even notice the springs.
I've included a picture of one the other is broken in exactly the same way
Hopefully somebody can shed some light on why this could happen. The car was driven exclusively by my wife until about a month ago has never been in an accident or used offroad.
The biggest shock they would have experienced was a speed bump or two which I would assume they could handled
This has me a bit unnerved knowing my family has been riding on these for some time as the point of breakage is well rusted
Also I'd appreciate any advice on where to get new ones at a resonable cost
Thanks in Avance
Bob

Defective springs !
Get MBUSA involved.