Hey Erwin,
We cannot log into customer sites, and it would also be quite a security risk to post admin information publicly or over email, so please do not share any admin login information for your sites!
To come back to your issue, it seems that the main problem you have is that things used to look like this, which is how you want them to look now:
But the problem is that things instead look like this currently:
Is this a correct summary of your current problems?
If so, then unfortunately there is not much we might be able to do here. There is nothing within The Events Calendar that would make the layout render like in the “Bad” example I posted above (i.e. the 2nd screenshot). So perhaps something changed in your theme or other software on your site?
My first recommendation is to go to Events > Settings in your wp-admin. Go to the “Display” tab, and then go the “Events template” option there. Try out each and every different option, and check on the display after each time you save a new option. Does the layout improve at all?
If this first step does not help, or does not reveal anything useful, then unfortunately the next best thing I can recommend is to test a bit to try and find out the definitive source of the problem at least. You can do the full troubleshooting steps mentioned here → https://theeventscalendar.com/knowledgebase/testing-for-conflicts/
Those steps will hopefully help narrow down the issue to one that comes from your theme, and/or reveal any involvement of other plugins on your site…
Let us know what you find!
George