Have you considered brute forcing order numbers?

[Danm72]

I'm not 100% on the structure of the order numbers, but mine is #61 in that screenshot and its prepended with 353 which is the country code for Ireland where i live.

Everyone else's seems to be 0011 and ascending from there. Surely we could get a better idea of the landscape if we bulk imported order numbers.

It will require brute forcing the mobile numbers too. Which is a 1/10000 chance, so the big question is around their rate limiting.