A wise UK based CA (not cabin attendant in this case) gave me a quote from the applicable act.
"The period generally specified by the Courts as a reasonable time in which an action should take place is fourteen days. That being the case, payments in respect of the straightforward, uncontested parts of any claim should be in the bank account of the claimant before the expiration of the fourteen-day period.
After that you can let the dogs of war loose and contact their company secretary UFS Director Legal and suggest they get their act into gear. Nicely of course....
I have a similar contention with a large middle eastern airline who seem to be unaware of section 75 but they have at least added "Refund" to their website rather than the original "Voucher" button.
The plot thickens.