One address for everything: efreet4845291@gmail.com
It is not a payroll, tax or legal help desk. The site deliberately publishes its counting rule so you can adjust the numbers to your own contract or collective agreement; it cannot tell you what your employer will pay or when.
This site is run by one person, in the evenings, so replies can take a few days. Corrections to the data are treated as urgent and usually go live with the next rebuild.
Please include the exact page address. Every page states its own counting rule, the holidays it subtracted and the dataset behind it, which answers most questions without a reply. If a page and a calculator disagree for the same country and month, that is a bug worth reporting immediately: the two share one rule and are tested against each other.