Topping up the paypal card is a purchase.

Unfortunately the paypal card is a bit limited, as my reading of the T&C's suggest it only allows you to load it with:

£1,000 per month, and
£10,000 per year

I don't really want to load it up a bit at a time every month - I'd rather just pay a lot in prior to using it. These limit stops me paying both the school fees (1st) and my tax bill (2nd), which are the only things where I really miss out on miles at present.