If you experience a defect, report this to your landlord as soon as possible. This should assess this and repair it if it falls under major maintenance. You can report a defect by telephone, but it is also important that you do this in writing, so that you have proof of the report.
If the landlord does not (timely) repair the defect, you can submit a procedure for rent reduction to the Rent Tribunal. This means you pay less rent for the period that the defect has not been resolved. This serves as a 'motive' to put the landlord to work. There are all kinds of rules associated with this procedure on how to make the defects known. The Huurteam can support you with this, so don't wait too long.