Hey Tony, thanks very much for your reply.
No unfortunately the auto electrician wasn't forthcoming with any information or explanation as to how he reached his diagnosis. I think it may have just been the easiest/ quickest option for him, regardless of cost. Yes I'll certainly go ahead and get a second opinion, thanks.
There hasn't been any collision repairs done recently, but I guess there would be a possibility that loose wires could be causing the problem, especially since both doors failed at the same time.
My son-in-law is handy with a multi meter, and he owes me a favour lol.