To pull up the cleaners over this - leaving early?

[Chicice]

I book two cleaners for two hours at a total of £60. This is called a general clean.

I have a ring camera so watched them arrive at 1pm but leave at 2.30pm.

I messaged them straight away and said I was disappointed that they were leaving 30 minutes early. She gave some excuse about turning up early but I said I’d seen them arrive on time.

She then said they’d cleaned through to a high standard and when finished they will usually leave. I said id paid for 2 hours and I’d like that filled.

I came home from work and inspected the house, it was 95% to a good standard but still some surfaces a bit dusty and they hadn’t been particularly thorough in corners and some skirting boards. I felt they could have filled the two hours if they’d been a bit more careful and thorough.

Cleaning windows, skirting boards and under furniture is classed as a ‘deep clean’ though and will be charged at £80 for the two hours.

But I tried to argue that they hadn’t filled the 2 hours and could have done some of the above to fill the time.

AIBU or are the cleaners?

I charge clients per job rather than hourly.

I perform an agreed list of tasks. I go when I am finished. No one is clock watching.
Sometimes I’m done a little quicker. Sometimes (if the client has been ill, had guests, been decorating) the clean takes a little longer and I don’t walk off the job and leaves things half done just because my time is up.

Think about window cleaners or hairdressers - you don’t pay for a 30 minutes haircut or 30 minutes of window cleaning.

I could have written this. It's occasionally irked me but overall the convenience of having a weekly proper clean makes such a big difference to keeping on top of things. I use a company so it's not always the same cleaners, some better than others at finding extra bits to do. Last few weeks been same ladies and they are getting quicker each wwwk but do everything I've asked