I am trying to determine what the cause of a broken spring is in our 2001 xcv70 with 125,000 miles.

Here is the series of events:
November we replaced the two front tires, moving the fronts to the rear. Not great tires, but we wanted all four to match. At the end of november, we had the struts replaced.

the car didn't feel great, but we had just started driving it (borrowed from our parents) never had a 4wd, and were coming from a saab, so we just thought it felt different. (silly, in hindsight, but that's neither here nor there.) The steering felt loose, and occasionally would jump if it hit a pothole at high speed - the steering wheel would sort of jump out of my hand. Again, just thought it was the 4wd or higher center of gravity, and meant to get the alignment checked.

So in March, the spring driver's side front spring broke. Just plain broke. Our mechanics explanation was actually that it was the fact that we got "the struts replaced, the problem just moves to the next weakest link." Whatever that means. When we picked it up, they urged us to get new tires and an alignment. I went straight to where we purchased the tires, because they were new. He looked at everything, said the car was severly out of alignment, tires needed to be replaced, etc. Good guys, said they were so bad that it was clearly a mechanical problem, agreed to get 4 new GOOD tires and an alignment, since it's a good car that we want to keep in the long term. After trying to align the car for an hour and a half, he comes to say there is something wrong with the struts, that the car is more out of alignment than any car he's ever seen, and that he can't get it into alignment. (It was out 3 degrees?, percent? on each side?) He said the struts looked weird and we should go back to who did them and get them checked.

Turns out, they put in the wrong struts. The tire guy could visually see that something was wrong, so my question is two-fold -

Would my mechanic have known that something was not quite right, that they just weren't fitting right, but just let them be wrong, or would it be hard to tell it was the wrong part?

And would the wrong struts, over a few months (including a road trip from NY to NC) cause the spring to break?

THe mechanic took full responsibility for the mistake, fixed them and and had the car aligned at no cost to us, and paid us for the tires, but I'd also like the 600 bucks back for the spring.

Thank you in advance for your advice!