@Elaine701
When we are talking about a large sum of money, I think it's worth persisting with CS. I have done it with success, but it was time consuming and very frustrating. I got my payouts in the end.
If the guest was refunded simply because they were unable to attend some games, that's not good enough. However, there is a chance that, after the guest realised they would not get a full refund (a lot of guests seem to think that any COVID related reason entitles them to this), they read the EC policy and told CS one of them had tested positive. In that case, CS might not inform the host, nor be willing to disclose information as to why the refund was given.
If the refund was given on the basis that the guest did not want to complete the trip due to cancelled games or worries over Omicron, then it is worth fighting as that is not an extenuating circumstance.