The problem was this section:
I agree to work from XX:XXpm to XX:XXpm
or 2nd time
agree to work for X hours…
both ended with: Overtime: For additional hours the charge is XXX amount.
However overtime is a “lax” statement in most countries and there is a fixed percentage of what is considered overtime and what not… so I got not paid for the extra 2 hours as it was considered “good practice” to just do so.
So instead you should always write:
after the agreed period has expired each hour is billed with XXX amount on top of the agreed fee, whereas the minimum charge is always an hour.