Canon 100-400 IS problem

Dear Friends,

I am facing a problem with my 1 year old 100-400 lens since 2 months. I was googleing it and found similar problem with one or two more users in UK. My problem is also similar. I try and focus on something by pressing the shutter button halfway, the image through the viewfinder jumps up and down indefinitely and the camera stops trying to focus until I release the button and try again. It will normally work the second time and once the focus system has locked on, the IS system appears to work as normal. The fault is worse when I have just turned the camera on sometimes not always.

While the image flicks up and down during the fault, the f-stop indicator in the viewfinder flashes onto 00 and then back to displaying the correct f-stop.
I tried to isolate the fault by turning the IS switch to mode 2 which not worked. I've also tried cleaning the contacts but not worked.

Thru Google came to know that this is because of IS system failure.

Any Idea how to get it repaired and how much will be the cost? Any help in this regards will be appreciated. Your suggestions and comments are welcomed.

Canon has got its Level IV service centre in Delhi (Barakhamba Road) as well as in other metros. Show it there and they will rectify it. Did you drop the lens or did it have a really nasty bumpy ride? The IS system appears to have got hit. The standard charge for opening and checking the lens is about 2500 rupees. Plus the charge for parts. I guess it should be max 6-7k, but it depends on what parts to be replaced. Is it on warranty?