Originally Posted by
GavT_london
If you want to be pedantic about it then yes - you cannot apply it to an existing booking - however there is ALWAYS the option of cancelling and rebooking with the 241 voucher - i was merely pointing out this possibility as a lot of people don't consider it (or indeed its pitfalls)
There are lots of comments referring to the amex 241 voucher but please remind that this voucher is only available to UK members. I am not sure for the OP located in the US but it is not available to mainland European EC members as far as I know.