Addendum completely overpriced????

Dear drywall installers,

I have a question regarding a supplementary charge. Due to time constraints (move), I commissioned a drywall installer/plasterer to quickly install 2 window reveals and a small remaining area with renovation board with corner beads. According to the invoice, a total of 2.5 m² of [Renovierboard von Knauf] was used. Now he wants to be paid 8 hours for this service in addition to his material costs. The total cost then amounts to over 730 euros. From your point of view, what is a reasonable number of hours for this service? In advance, he did not want to give me an approximate number of hours when asked. By the way, only the installation and smoothing. I sanded it myself the next day. Best regards

A few questions:
- How many hours was he there?
- What is the hourly rate according to the invoice?
- How much material is on the invoice?
- Travel expenses?
- Gross or net?

Be glad that someone even showed up for the [Minijob]. However, it is his stupidity to report hours now instead of a flat rate ...

"Nachtrag" => expensive
"Zeitgründe" => expensive
"kurzfristig" => expensive
"kleine Restfläche" => expensive

Small areas are always more expensive. Would have negotiated a flat rate

Yes, that is expensive. I paid 400 euros for a similar service. But since you didn't agree on anything, he can definitely demand that.