HI Henri,
These are “standard” two position rocker switches and thanks for pointing out the supplier of the panels (VDO). these switches are generally pretty long lasting but they are mechanical and made of plastic, and therefore prone to breakage after a length of time and exposure to UV. The LED is a repeater so just an indicator. What you describe is simply that the contacts are not working by the sounds of it so Simple replacement by desoldering and refitting a new one should fix it.
Best to contact them for a replacement switch…. although replacements are available from many electronics suppliers
Mike