There are two options available for you about the ticket. You can ask for your refund if you do not intend to use the ticket again. If on the other hand that you want to use the ticket for other edition, then you cannot ask for a refund and you can use it for the 2022 edition. If you are asking for partial payment, it is not possible. Organizers have made it clear that you are not entitled to partial repayment of the ticket money. It is either you get your money complete or you do not get at all. Currently, they can only refund the entire purchase, there is nothing like a part purchase refund.