A new parameter at voucher that define if the voucher is allowed to keep the remaining amount of the voucher to use it later.
With this new parameter, when contact pays for their order which the amount less than the voucher amount, the remaining amount of the voucher is kept and could be used for next orders (instead of sending to Credit note or debtor profit).
Contact buy the new voucher as usual.
Use of the voucher on Ticket Shop
Contact could add as many voucher as needed (until it reach the order amount), the remaining amount will be kept with the message as below screenshot (voucher identifier FDF4-C886-95C0-3966) :
The remaining amount of the voucher (voucher identifier FDF4-C886-95C0-3966) could be use for the next order: