Refund of vat

I was on a tourist visa in thai land and bought an iphone 14 pro last year from bangkok from apple store app

but when i reached airport for vat refund

they refused to give me vat refund and they asked for some kind of stamped forms

beacuse I purchased iphone online so i have only online receipts but they didn’t accept them

now i want to know if i buy an iphone again online like preorders how can i get the vat refund thanx