Have you tried reaching to Machines via email? I know their response time is a little slow, about 2-3 working days per reply, but perhaps you can get an answer directly.

Thing is, alot of brands do not ‘personally’ manage these official stores, they employ 3rd party to manage these platforms therefore you won’t get a like for like service - but they should have attended to your request.

Don’t give up, escalate this matter to Shopee, Machines social pages or email because it’s your right to demand for a receipt, regardless of a big or small purchase.

Cheers!