I have found main dealers to be indifferent to DIY mechanics - there's no money in it for them you see! They will have access to all the technical info put out by Suzuki, but are probably just not willing to help. If you bought the car from them or have it serviced there, try pointing this out to them. Or, try another dealer or Suzuki UK.
Ref the main dealer attitude. A few years ago a mate of mine went to the local Volvo dealer asking for advice. He was told that customers pay £30 per hour for information, and that it wasn't available for free.
Tried to get a wiring diagram for the radio in my sons Peugeot 206 and guess what, Peugeot Main dealers don't have them. I asked the obvious questio, "how do you work on the radios then?" to which they replied, "we don't, we send them to a specialist to be done" doohhh.
If the Suzi is new there won't be a Haynes manual out yet. Haynes manuals do however have pretty good witing diagrams that even an electrical dunce like me can understand.
Well, with Block Exemption around the corner, Main Dealers will have to make technical info available to the aftermarket. This (I think) only applies to emission related parts of the vehicle, but I'm not sure.
I must admit I don't like dishing out advice/info to independants etc but I try to be as helpful as possible.
Just to unhelpfully point out that the dealers are there to make a profit on working on your car, not acting as a photocopy service.
We are an independent garage and struggle on occasions just as you are. We usually have to grovel & beg.