We couldn't possibly upsell on the day as described by Paul, as we haven't got time being fully book all of the time, sometimes weeks in advance.
If you've got these great offers why not tell the customer at the time of booking instead of putting them on the spot on the day. Sure, some will say yes because they want to, but others will do it through feeling the pressure to say yes, but avoid using you in the future, which might explain why you've got time to do all these extra jobs on the day. 
I.m sometimes weeks in advance too mate so dont worry about me....if i ever get to your operational set up and level i'd want to be months in advance...thats fully booked..
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can't upsell or offer extra on the day as too busy and booked up... but can do free things like small rooms and rugs..
I do mention at time of quotation but i also know when you are there there can also be an impulse thing.. once you set and they see what you can actually do.... and i've found that sometimes when ive asked the custy when there some of them say well i didnt like to ask i was just going to book you up again to come back for that....
I manage to fit it in as i structure my day and workload .... there is always time to make a bit extra £££ if i can
... so if you're on a job and the custy asks "oh by the way could i just have my H/S/L done too while you are here"... you really turn them down and say you are too busy???....
I dont hard sell mate and dont put custys off or push anything..... i communicate in a nice cheerful polite manner.. not sleazy or smarmy or anything... just honest and trusting..