There's just too many things wrong with this as I've detailed above. With a lack of any kind of helpful response. I'm afraid I can't wait any longer as my clients won't accept a non functioning advanced search feature. It appears you have a lot of work to do before it is fit for purpose.
If you have no solutions then I guess I have no choice but to get a refund from Envato.
It's a shame though, as if it worked it is a better looking search than the rest on offer.