Paying 500 Bt for a tuk tuk ride that'd be less than 100 Bt by taxi and then expecting the tuk tuk driver to change a 1000 Bt note leads me to believe the tourist is not all there.
Apparently, I sent an email enquiry a while back and that was their follow-up email.
But for me, offering 10% when most UK banks offer about 5% and Thai banks 2% sets alarm bells ringing.
Just sounds too good to be true but if it's legit, I'd be shocked.