Thank you, Canon unlike ourselves provide standard repair prices for there equipment, subject to inspection, thereby you shall pay £102 at best and more if they require to estimate after examination, we do not operate a menu pricing system and provide a cost after examination thereby we know cause and costs when we provide you with a detailed estimate, we make no charge for this estimate and find that it suits our business model. Canon do not wish to provide estimates, however this means that someone with a minor repair subsides those with more extensive repairs... without examining your lens it is not possible to say what the cause / costs are likely to be. Best you decide which method of obtaining a repair costs suits you... It certainly sounds like the zoom guides in your lens are the source of the problem, they may simply require re-fitting, securing and calibrating or if the inner zoom helicoid will no longer accept the screws and require replacement you would be up around the £100 + vat mark...
, then I was like 
). It feels a bit intrusive sometimes so I tend to try a stick back with 200mm +. I Like to say 70mm is as close as I get (erm...). So I tend to keep a little further back than most.
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