Switzerland does not allow this.

http://www.webster.ch/humanresources/overtimepolicy.html

> All extra hours and overtime [...] must be announced to HR department before the 10th of the following month

> Any hours that are not announced respecting this time frame will be excluded from any form of compensation.

I have a friend who did this - it works. I doubt they'll have to sue, probably a simple demand letter will be sufficient.