Did you explain to the concierge desk that you do not want to do the City Tour? During my last stay there i've precise that to them and they simply booked me the entrance through an online reseller.

The prices are pretty high - 35.00 Euro per person compared to the face value of 8 Euros. Compared to this, with enough time available, IMHO the 3 hour City Tour (60.00 Euro per person, operated by Autostradale company, not by the hotel) is great value. I think that this is also the reason why they push for City Tour.