Hmmm. It looks like the coopculture folks have done some work to their tour reservation pages..which is good as it appears to make locating remaining available tickets for individual dates easier than previously.
What's odd, though, it that they look to contain some errors. For instance, the right-hand column of this page lists the "didactic" adult tour prices for the underground or belvedere at € 9,00 +€ 2,00 reservation fee.
When you go to the actual ticket purchasing pages for both of these (I'm testing tours in English), text states that tours are € 5,00 + reservation fee "just to collect onsite". OK, sort of makes it sound like there's a discount for collecting in person versus printing at home. However a test purchase of tickets still available Dec. brings up a per-ticket total price of € 11.00 (€ 9,00 +€ 2,00), which has been the usual price for underground tours. These are for the over age 12 tickets.
As I can't test-book all the way through the process, I can't see where that published € 5,00 (€ 7,00 with fee) per-tour price comes in, unless it's a lower collect-onsite versus print-at-home option. That doesn't appear to be the case, though, and could be an error? As the forum sees a lot of questions from confused ticket purchasers, I'm just curious if anyone can shed some light on this discrepancy should the question arise?