Can the system warn me before a held booking expires so I do not lose the fare my customer has already agreed to?

Yes, in most cases this can be automated, as long as the supplier tells the system when the hold expires. When a flight or a hotel is held rather than issued straight away, the airline or supplier usually returns a deadline along with the booking reference. That deadline can be saved against the booking and used to send a reminder to the staff member handling it, well before the time runs out.

Once the deadline is stored you can decide what happens around it. A reminder can go to the agent who made the booking, a second one can go to a manager if nothing has been done, and a payment reminder can go to the customer. The booking can also sit on a daily pending list so nobody has to remember which files are still waiting, and no one needs to keep their own spreadsheet of expiry times.

There are honest limits. Not every supplier returns a clear time limit, and some do not allow holds at all, so those bookings have to be paid and issued at once. Some airlines also shorten a deadline after the booking is made, or release a held seat early in busy periods, and the system can only act on what the supplier has actually sent. For that reason the reminders should be set to fire earlier than the real deadline, so you still have room to chase the customer or rebook.

A good next step is to list the suppliers you use most, check which of them return a proper expiry time, and agree with your team how early the first reminder goes out and who follows up on anything still unpaid.