Hello and welcome . The rear suspension on a w203 C class is just a (pretty upright ) spring and sperate shock absorber , nothing fancy. It must be a W203 as it is a 2005 car. W204 started in 2007.
Are you talking about this ? If so pretty much the entire W/S203 range had the same set up .
Thanks Pete, sorry w203 - it’s actually a front coil that’s sheared and I’m pretty sure there isn’t a 5 link set up on the front - the garage was saying it could be either that or standard ……
You will have a Mcpherson strut and track control arm set up. The strut will need to come off to change the spring, not a big job three nuts at the top and two holding it to the hub/bearing carrier. The tricky bit is compressing the spring as they can be a bit nasty if they escape under compression. Better change both side and make sure they properly rated for your car.
Front springs of various quality widely available , hopefully either the part number or colour code is still visible on your old one making buying new ones pretty simple.