Can the price of a hotel change between my customer searching and actually paying on my portal?

Yes, it can, and that is normal in hotel distribution rather than a fault with your portal. Search results come from supplier systems that are updated constantly as rooms sell, as rates open and close, and as promotions start or finish. What your customer sees on the results page is a snapshot of that moment, so if they browse for a while, compare a few options and then come back to pay, the live rate for that room may no longer be the same.

To deal with this, a hotel booking flow normally includes a recheck of the selected room just before payment is taken. If the rate or the availability has moved, your customer can be shown the updated price and asked to confirm before anything is charged, or the room can be released and the search repeated. How strictly this works depends on the supplier behind that particular hotel, because some return a short lived price guarantee once a room is selected and others do not guarantee anything until the booking is confirmed back to you.

It also helps to know that cached results make searches feel faster but slightly increase the chance of a change at the payment stage, so there is a trade off between speed and accuracy that can be set differently depending on your plan and your suppliers.

If this matters for your business, check with us which of your connected suppliers support a price recheck step, and get your staff used to requoting a room if a customer sits on a quote for a long time before paying.