If you are having this problem I would do a check list on a A4 sheet showing all your services,you can tick everything the customer wants done, which would leave con roof cleaning not ticked !.It just stops any confusion usually on their part Regards Hotsteam
We had a spate of these a few years ago, now our Quotation Form has the words:Quotations do not include conservatory roofs unless specified.They get a completed Quotation Form with other info (Rain Guarantee, T&C's, description of WFP) so there's no dispute.
'Is the conservatory roof not included in that price?' - I usually just say, 'Yes', then study their reaction...