@starbreaker@danjac I disagree with both of you.
First of all, if you are waiting for the client, you are working, so it's hours to be reported, whatever they say. It's not the client who writes the timesheet. Write something they accept.
Second, do not work for free. Either stop at 40h, or report 60.
If either of the employer or the client is not OK with this, move on.