Eurostar spare - London to Paris return

[Gary25]

I booked this after we got into Semis for £224 return but unfortunately I'm not able to go to Paris. Leaves from London on Thursday evening 26th, return is Sunday morning, 29th. It was £450 last I checked for same trains I booked but don't want anything extra, just want to get my money back what I paid. Anyone interested or know anyone who might be just let me know. Thanks