Originally Posted by
bakera
Why not just overpay your card. E.g. pay a couple of £k into your account so that your available balance is £card-limit + amount-overpaid
I believe that's a breach of the card T&Cs (same with pretty much all CCs), and could lead to your card being closed - that said I've seen reports of people getting away with it, so comes down to risk appetite.
In any case, I think ringing Amex to ask for a limit increase is the first port of call...