Hi Agnes
If it's your client and your business then its up to you to negotiate whether or not you charge for bank holidays. When i cleaned an office block i never charged for work not done but thats not to say another company would follow my example. If you want paying for it then say so, if you dont think that they will be happy with paying it then make sure that the price you charge allows for any time where you can't work...At the end of the day it isnt the companies fault (not that i am saying you said it was or anything) that we have bank holidays and certainly the owner of the company who's offices i cleaned made it quite clear that his life would be a lot easier without them lol.
I dont think that if they agreed to pay for the bank holiday you could charge more for it (whether worked or otherwise). So the choice is this: ask them to pay for it OR make sure you budget for it in the usual price OR suggest that you still go there on bank holidays and do other work aside from the usual daily cleaning (if neccesary).
As for the bins issue, yes, ok, if you do X, Y, and Z and it's not in set in stone then naturally things that you do above and beyond whats been agreed will add up BUT i would have thought that this issue with bins should be brought to the attention of the person who hired you so that you can talk it out between you. The problem is that by asking these questions on a forum (and i'm not for a minute suggesting that you should'nt ) is that because there is no right or wrong answer the replies will be biased by the personal feelings of those who write back.
I, for example, am quite likely to go too far beyond the call of duty to please a customer, but then i work alone so there is only me to consider. Someone else who has staff ( like you i expect?) may need to take a slightly firmer approach BUT at the same time obviously being flexible still (after all they are the client), the last thing you need is a 'them and us' scenario...Without knowing your client personally i cannot say why it is that you dont know how to 'approach' this one? Are they not nice people to talk to etc?
cheers
stephen