Mondeo Broken Suspension Springs

My Mondeo (1997 2.0i 121K miles) failed it’s MOT yesterday due to broken front suspension springs (both sides). The garage says the car should not be driven. I’m OK with the advice, but the problem is the car was serviced by the same garage (a Ford agent, not a main dealer, which I have been using for the last 4 years) less than 4 weeks ago. I had it serviced before going on holiday to France and it was too early to get an MOT done at the same time.

I have driven the car since the service, and haven’t noticed any bangs that might have indicated the springs going, nor have I noticed any differences in how the car is handling.

So, a couple of questions:

1. Should the garage have spotted the broken springs during the service? The car has been serviced twice by them since they did the last MOT. At the last service they also changed the tyres so the wheels were off the car.
2. What is the likelihood that both would have broken in 4 weeks and approx 1000 miles of driving without me noticing?

The cost of replacing them is not an issue – it’s more about the inconvenience of having the car off the road for a couple of days, and more importantly having driven the car to France and back in a potentially dangerous state.

Any thoughts would be welcome.