The Seats on Eurostar to Paris are already sold out for that day :/ 

How do you know? Can you show me where you found that? I don’t belive you work for eurrail? 

Im confused- does Eurrail not have their own trains? I am aware that eurostar is sold out but that’s a different train? 

I dont work for Eurail but i used a secondary page where you can reserve Eurostar with Inter or Eurrail and even that page shows no options for that day i assume many tourist visit London for a extended weekend as the thursday before your desired traveldate is a Bankholiday in many european countries 

I used the website of B europe (Belgian Rail) https://www.b-europe.com/EN/Booking/Pass#Outbound

In this community are just a handfull of supervisors of Eurail (usually online Monday-Friday within standard office hours) 

Customer Service department can be contacted by this form https://eurail.zendesk.com/hc/en-001/requests/new

Eurrail is no traincompany

Eurail have contracts with many european Railcompanies that they accept the Eurailpass how ever sone companies like Eurostar offer just a specifc amount of seats for Eurail user and especially on popular dates like extended weekends or Easter they are often sold out for Eurail user. 

got it! Thank you. I think I’ll need to get my pass refunded then do you know how I can do that?

Go to your account at interrail, and there you can usually see if you can cancel your pass and what it will cost.