When can the guest receive refund from an alteration initiated by the Host

[Coln0]

Dear All, I have the situation where a guest booked my place instantly, but later on I realised he actually coming with a children who is below 2 years old. Based on my description this children's fees should be waived. I alter the booking and lower the price. The guest accepted the change but he did not receive the refund from the price different. He was using the debit card so I suppose the transaction should be instant as it charged or refund. Have anyone experience this before and could give me some advise? The guest is waiting for my response now. Thanks and have a nice day.

[Bob43]

I have not had the same experience, but my guess would be that the amount the guest will get back, will be paid the same day as your amount, the first day after check-in.