OP here, to give an update.
1. There is a euro refund amount pending on my booking.com wallet which is essentially a credit that I could withdraw if moved from pending rewards to credit. However, having phoned them about the refund and spending the obligatory 45 mins while the CSR goes and check with others in there, I am still being told I won’t be refunded till I can show proof of payment with the euro amount clearly shown on a bank statement.
2. This morning I sent a Letter Before Action requesting a refund from the property via email (a pdf letter attached), giving the background and requesting payment within 7 days from today’s date before I go down the UK small claims court route. I also sent the same letter by registered post to two addresses in the UK I could find for the company. €16 per letter for registered post is criminal btw.
The property replied to my email saying the amount has been refunded to me by booking.com which is not true.
3. Conor Pope has not replied to my request for help.
4. Booking.com don’t seem to reply to reviews on google or trust pilot, so as of yet I haven’t left a review there.
5. I next plan to send a similar letter to booking.com in the Netherlands with proof of the efforts I have made in relation to statements snd screenshots, replicated by an email but an email will likely go to some generic customer service email address. I will look to go down the small claims court route in Ireland against booking.com before going down the European small claims court, possibly in tandem.