hi there.
it all depends what the spec for the job says. we stipulate that the cleaning will take place at x oclock. Now if you have some decent t and c's you will have a clause in there that states, that if access is denined by the client at the time specified to do the cleaning, then it will be deemed that service has taken place.
therefore the request by client to do a clean at 12.00 would be an additional service.
also to be honest, i would not allow a client to get away with always turning up late to open the premises. i would have had it monitored for a maximum 10 days, then visited and sorted the matter out. if you dont do anything about this items then the client believes that they have the upper hand.
if you booked your car into a garage for a service then turned uo 15 minutes late, then you would expect to get the vehicla back 15 minutes after the original agreed time.
so why should cleaning be different, you have agreed the time for cleaning, your cleaner may have other time sensative sites to go on to after the first job, therefore the delay may make them late for other sites. therefore upsetting other customers.
i hope that makes sense.
regards
martin