Hi mate, congrats on your purchase of your V35.
Yes, the window/door lock issues are some of the common problems on the V35, and it often happen every 2-3 years depending on the usage of the car. The procedure you mentioned of going to an auto electrician or a mechanic, getting the quote and faxing it to the warranty company sounds like a right procedure. My suggestion, in your case, is to fix it quickly before the warranty runs out.
Are you sure you only got 3 months warranty time frame? I bought mine from a dealer in Perth and I took up 3 years warranty time frame. Also, my dealer got a car service centre together with the show room so they already have auto electricians and mechanics. So when I had my window/door problems, I just went to them. They fixed it up, gave me a warranty slip with all the details in it, and I send it off to the warranty company through post.
Good luck with it. Let us know how it goes.