Same problem for me. Looks like the voucher code deducts a certain
amount from the price rather than reduces it to £1. Can only assume the
price has gone up on the buds so the reduction of £178 (IIRC) nets you
£41 total.
Have you logged into your my02 account before using trying to use the
code? Had a similar issue and this solved it... Now I've got the issue
that my code isn't deducting the promised amount...