For some reason this method of payment to get galaxy points seems to be unavailable (not visible when you're trying to buy GP) at random periods, it was available somewhere during the summer, then it disappeared until the bane came, and now it's gone again.

I'm not necessarily looking for a fix but I'd like to have an explanation on why this happens when I've never seen any of the other payment forms become unavailable.

I think that's out of Dan' hands. FB handles the payments.

...could be that you're buying different amounts of GP. I know that I can't buy over £30 worth of anything online when using my mobile.

That could be true that it's on facebook's (or even Interac itself) end rather than Dan's, as for the amounts, I've bought 50$ (550 GP) amounts before so I doubt that's the issue.

It's available for me.

Hi!

Facebook provides and manages the payment methods available. If you are having trouble with a payment option, please contact Facebook Payment Support.