what durations have you pinned these houses to take?
We clean student properties move in/out on a monthly basis, they can take up to 12 hours sometimes per house (team of 2 or 3) so on site 6 or 4 hours, depending on the state, sometime very rarely we are lucky and have 2 cleaners for 2 hours.
so your 4 bed house in the worst state 12 hours minimum we charge is £15 an hour per cleaner or so if its in a bad way. £180 per house.
if they are easy ones, minimum £50, 2 cleaner for 2 hours.
Holidays lets might be a bit different, but i would have based it on these student properties.
Thanks
Lisa
i would renegotiate if i were you.