900ss throttle bodies

Hi all, just wondering if anyone had any advice to give about throttle bodies? I’ve recently acquired my 1st Duke ('98 900ss fuel injection) which is very lumpy at low speeds and was told that the throttle bodies need synchronising. I’ve been quoted £250 to do the work from Riders of Bridgewater in Somerset. Bridge in Exeter wouldn’t touch it as it’s not a model they are familiar with for some reason. Is there a more economical way of having it done or it is it just one of those things and I should just pay the man? Any advice on the subject would be greatly received, cheers in advance.