Delay in feedback results in financial loss

I am truly disappointed in the service I received from Flight Centre. My husband booked a BA ticket with them and we subsequently requested to change the date of the flight. The flight change request was made on a Friday and we only received feedback the following Thursday, apparently due to a delay in response from British Airways. I could not contact BA myself as we had to change the flight through the travel agency. As a result in the delay in response we suffered a loss of more than R1500 for an additional ticket that we wanted to buy, as we had to wait for the confirmation of the flight change before we could purchase another ticket to ensure that both are on the same flight. I contacted the call centre and they were very friendly and apologized for the unfortunate incident, however the apology does not change the fact that I suffered a financial loss. I expected that the agency would put some pressure on BA for a response, otherwise what is the point of making use of a travel agency. We were in the process of booking a US trip with Flight Centre as well, but after this incident Flight Centre will not be our preferred travel agency.