UK Service /repair recommendations for 100-400L please

My old Canon 100-400L lens is getting rather old and needs some repairs ,servicing done.Front end has a slight dent in the filter can't get the filter off and every now and again the IS seems to flick the image around before shutting the camera down ,although this could be a contact problem with the camera body.
Any recommendations for a good repair /service facility in the UK and if possible ideas of costs [I know how long is a piece of string LOL] .
I only use the lens a couple of times a year now so i will take that into account as well as i now use a g1x mk11 camera 99% of the time.
Ta

I sent my 17-40 to Fixation and they did a good job.

mkkaczy wrote in post #17998426
I sent my 17-40 to Fixation and they did a good job.

Hi ,is it these guys? http://www.fixationuk.​com/ ,Thanks

Plus one for fixation, or there's a service centre in Glasgow I believe that gets good things said about it.

You could try Canon themselves - I used them a few years ago and were the cheapest of the bunch for what was needed

Trumper wrote in post #17998430
Hi ,is it these guys? http://www.fixationuk.​com/ ,Thanks

yes

Thank you .I took the lens and the 5d mk11 out for a walk today [last photos taken with it were September last year ] and looking at the photos on the camera i was really disappointed however getting them home they came out quite nice,i had forgotten how big and heavy that lump is though LOL.