So my 2012 focus has a seized eccentric bolt on the rear control arm. Apparently its fairly common and a pain to get done as 2 places have refused the job. How bad of a job is it? Would the cost be worth it compared to the cars value?

Is there other work that needs doing ? Curious as to why you want to remove that bolt, think it called concentric.

For the bolt, try yourself, wire brush the area, plenty of penetrating fluid over a couple of days. Good fitting spanner or heavy duty socket and extended handle. Tighten a little to break rust seal and unwind a bit at a time.

For the first couple of turns, wiggle underneath and have the car on all four wheels. It may take some efort you don't want it moving !

Went for wheel alignment after replacing the front offside wishbone and CV boot, shop said 4 wheel alignment was 15 extra so said may aswell and then they mentioned the rear bolt. Said they wouldnt touch it and just did the front. Shop showed me the nut and youd need to at best weld another onto it. Control arm isnt looking the best either so hence the reason for asking

@IrishMk3 I did the whole rear suspension on my MK2.5 Focus last year.

My eccentric bolts refused to break free of the bushings they sit through even though the bolts were off. The bolts rust and bond into the metal tube that goes through the centre of the rubber bushing. Some of these garages are wimps.

If you can DIY then cut to the chase and do as follows:

Get a reciprocating saw and carbide blade for cutting thick steel (the bolt). Cut each bolt in the gap between the subframe and the control arm. You should be able to get away with just one cut per bolt. Then get a punch and put it through the hole in the subframe the end of the bolt you cut off is, and give the punch a few progressively firmer whacks with a hammer. That should break the rust bond and the bolts should come off. If not, then cut the other end of the bolt.

The trickiest thing about doing the suspension on the drive is setting the ride height. You'll find the ride heights in Haynes. You must only torque the rear suspension arms bolts when the ride height is correct.

The garage will be fine to do the rear alignment if the bolts are new. Just be sure to get decent quality bolts like INA (Shaeffler).or Febi brand. And while you are at it change the rear control arms, that way you have new rubber bushings in them too.