I had some work done on my house recently. I had a written estimate for the work in advance that said the time to do it would be "approx... hours" and the materials required would be "up to ... items".
When the workmen turned up they were at my house for only a third of the time estimated, and used only a third of the materials estimated.
I was astonished therefore to be invoiced for the full amount.
AIBU to refuse to pay the full amount?