Search date don’t work

Hi I have a problem with finding buses available on certain dates. Let’s take an example.

I have 1 bus that leaves every Monday at a certain time and another bus but this one always leaves on Mondays only on certain dates.

When I search through the search form I get all the buses that have Monday as the departure day, including the one that is not available on that date. Furthermore, that bus turns out to be available and bookable even if it isn’t there.