Can we change the concept in the middle of the design process?
The customers should consistent with the concept they ask before we approve their order. If there is any feedback, it should be in line with the concept they asked earlier. However, if it is urgent, we may accept a new concept, but there will be an additional charge and the turnaround will be added since we should restart redesign the slides.
Also the customer should stick with the file that you attached earlier, you should not suddenly change the file that should be redesigned. It can be acceptable as long as their order is still not approved, not in the middle of the process design.