Supplier Credit and Refund

Looking for some direction please.

I have a client who was to attend an event and paid the invoice in the current fiscal year.  Because of Covid the event was cancelled.  The event refunded 1/3 of the payment (direct deposit into bank account) and has credited 2/3 to a future event.  The original payment was made in March 2020.  Refund/Credit took place in June 2020.  March's bank account has been reconciled.

How do I record this?  I did not record it as a prepaid expense. I'm using Sage 50 Canadian Version.

Thank you for your time.