Canon 300 2.8 non-is lens repair

[Cealy]

I have the first version bought in 93 and love this lens with the integrated collar. It has seen 5 Olympics and just this weekend started having Error 01. The mount needs to be changed but Canon refuses to even look at it. I live in Montreal. Are there any third party service providers who can do this? I really dont like the design of the newer lens with the external collar. I have seen many a 300 hit the deck because the lens slips out of the collar.