They’ve ‘reserved’ £99 ever since pay-at-the-pump was introduced quite a few years ago where I live, Steve, and I understand the reason for that practice. But I’m an inveterate on-line account checker/reconciler every couple of days (must be something to do with being an accountant in my past life) and I’ve never seen £99 charged to my card/account followed ‘days or even weeks later’ by a credit for the difference between £99 and the actual charge, only ever the charge for the actual purchase amount.