Broken spring is one thing, and lower suspension arm is another thing.
You firstly want to make sure that they use oem parts, especially with a C32 and the lower arm, and do both sides.
You have a lower control arm and an upper control arm. Lemforder make them for Mercedes.
The Lower ones are the ball joints that go, the rubber simply perishes.
You will be looking at around £100 for the lower arm each side (always do both).
The upper are around £50 each and may as well do them when it is in bots anyway.
So £300 parts so far.
The springs are £85 approx. each. again do both.
How many miles has the car done, new shocks will be around £180 the pair, and obviously if the car is coming apart maybe an idea to swap them if it is close to 100k, they start to slightly go around 60k and get worse as the miles rack up, but slow process so you won't really notice.
Labour will be about 2-3 hours to swap the spring and arm on one side, maybe 4-5 hours to do the lot.
Is the spring and arm on the same side even?
I would get it done, it will make a massive difference.
Get them to do drop links, anti roll bar bushes and top mounts as well, new front end then and will feel tight, that lot is around £60 and make the world of difference.