Law in Belgium relating to Refunds

I signed up to ride the tour of Flanders in 2020, due to Covid this was cancelled as was the rescheduled ride in 2020. The 2021 ride has now been cancelled until September 2021 with an alternative to ride in April 2022.
I have asked for a refund as the company has had my payment for nearly 2 years.
The reply I have recieved tells me I must prove with medical certificate or some other means as to why I cannot attend, or sell my entry to a third party. What rights do I have under the law?