If you have booked your ticket through your buscenter account you can redeem a voucher in exchange of a cancellation. The value of the voucher will be equal to the value of the ticket purchased diminished of a 25% penalty fee.
To redeem the voucher enter into your account and click on ticket management and then on refund ticket, continue following the procedure.
The voucher expires in 3 months and can be used to pay a a new trip for the same route at one condition: the price of the new journey is higher than the value of the voucher.