We went to Morocco for the first time last summer and in a place called Marina Smir we found an MRI office which said they rented out apartments. They took us to a lovely complex nearby at Marina Beach and showed us a two-bedroom apartment which they said they could let us have for two hundred euros per night. We immediately took it and paid up front for two weeks (13 nights.)
We were only there two days when Security and an "owner representative" arrived and asked us what we were doing there. We told them and they were most annoyed, both with us (at the time) and with the two guys from the MRI Office. They asked us to leave and we explained we had paid. They said that was our problem and that MRI had NO CONNECTION with rentals for that apartment.
We eventually sorted out an arrangement with the real owner and stayed for three more days. We then went through an incredible experience in trying to recover the money we paid MRI. We got most of it eventually. We tried taking them
to court but it was next to impossible in Morocco and we subsequently heard similar nightmare stories from other people who had been duped in the same way. Seemingly this is fairly common practice with so-called Rental Agencies in Morocco. They hope the real owner is going to be absent for some time and just chance their arm!!
Bottom line: Do not rent from MRI or ANY agency in the Marina Smir area! We did find friends who had a success with a group called "Owners Direct" who seem to be a reputable firm.