I think customers perceptions are always leaning towards businesses charging to much , but in reality they have no idea what your cost of operating actually is. Sad but I don’t think there is a fix for your problem here. I do think as long as customers are treated with compassion and respect that goes a long way. You should be able to give them some idea if not an agreed price before they start. By doing this the question is taken out of this transaction on the front end and not the tail end. Better outcome. Best Mike