Q. If the client is amending the holiday but is still travelling with the same operator/if the number of passengers change in the booking.

Firstly you will need to speak to the Operator concerned to see if the changes are possible. Detail this conversation in transaction notes.
Amend the holiday details by accessing the transaction details screen.
Amend the costing details in the costing screen. If the costing has changed dramatically reduce the original cost to zero by entering cancelled on the next available line together with the original full amount as a minus and then underneath detail the new costing.
OK the costing screen and OK the transaction details screen
If there is any difference in the number of people travelling amend the header.
Amend additional details if applicable
If there is an additional charge payable by the client – collect the money. In Traveller go into payment entry and issue the client with a receipt.
When the amended invoice is received from the Operator enter this in document entry not forgetting to enter the new amounts of commission and vat.
Refund any monies due to the client (if applicable)

NOTE: IF THE CUSTOMERS ARE CHANGING THE HOLIDAY AND THE OPERATOR THE ORIGINAL BOOKING MUST BE TREATED AS A CANCELLATION