I've always charged time and a half on bank holidays if I work it and normal price if I don't. My parents have always stayed with their children and I've been payed as normal. This morning one of my parents have said they need to send their child on Friday for a couple of hours as he has 'a few things to do' 
I normally charge £40 per day as I have him from 5.30am, should I go ahead and charge £60 (time and a half) or is that too much because
A) I've only just been told and was looking forward to the bank holiday off.
B) I know that his dads not in work (mum told me) and feel he wants a few hours to himself.