Aaron Autos in Leeds, did mine the other week, £1400 cheaper than Renault wanted for a pair. Don't want to scaremonger, as I paid to have them done, as it is a bitch of a job. If you are not careful when removing the old balljoint and don't have heat and a good press, there is a big chance that when you press the balljoint out, it can take part of the alloy wishbone with it, due to dissimilar metal corrosion and after a few 1000 miles you have a new balljoint wiggling about in a f****d hub! I know a breaker ALS Performance parts in Carlisle are selling complete sides for £175 hub knuckle and retainer ready to bolt on.