re: all the 'HSBC unable to contact supplier' gubbins: I was informed while paying for a pub lunch yesterday that HSBC's authorisation system was down, meaning attempting any transaction with an HSBC card (chip & PIN, or just getting cash out of an ATM) would fail. Dunno if this could explain why certain cards weren't working. Especially as the HSBC system on the Iyonix site will have to authorise all transactions.
PS. Luckily, I don't use HSBC, so I paid for my food without incident, and the mixed grill was delicious (o: