Not BA related, but to underline the point about browsers. I have a voucher from buyagift which if I try to use on my laptop, whether on Chrome/Safari and even with clearing cookies/incognito, it just says voucher invalid - not simply hanging but a clear message that the voucher details provided were invalid. I queried it with CS, they said try a different device, tried on my phone and it worked fine. Infuriating. But a datapoint nevertheless that there can sometimes be fairly simple solutions in such cases.