Classifieds acts strange

Classifieds is acting very strange on my site:

1) I have activated the credits system with a default credit value of 40 when a user signs up. When I log in and create an ad, I have 40 credits available. When I click the renew tab (or create a new ad), the credit goes to 22601. If I end the ad and renew it, the credits are doubled. I don't think this is how the plugin should work.

2) I can't get the listing on the main classifieds page to work. Products are listed or aren't listed. When I add a second ad as a user, only one of those ads will get listed. Some ads aren't listed at all.

I have deactivated the plugin, deleted the virtual pages, reactivated the plugin, uninstalled and reinstalled it, deleted the wrong credit entry in the wp_usermeta db table, ... nothing helped.

The classifieds plugin is a core component for our site and we need to get it to work. I hope that the other plugins we use from you will work without a lot of headache.

Greetings from switzerland
Chris