Do you need a tour operator? Have you considered doing it on your own? I made a friend from Cartegena and this is what he sent me for our up and coming trip while we are there. He works for the US Embassy.   The port is only about 10 - 15 minutes from the port so it is easy to get to the Old Town and back without worry of missing the ship. The Old Town is a must see in Cartagena. You can do your own tour and take in the majority of what you want to see and do and be able to do it at your ow