Crest INFINITI

We bought our Infiniti QX60 at Crest but have constantly had transmission problems that Crest has been unable to resolve ever after 18 months. Their service agent hasn't been very helpful either and it takes a long time to get a loaner vehicle even when you make an appointment. Usually I have been able to get a loaner in 15-45 min but recently I waited more than an hour to get a loaner and then the person says that they actually don't have any loaner. Could I wait another hour or would I come back with a new appointment? I am guessing that they discourage QX60 owners like me since they don't have a fix for the QX60 transmission shuddering at low RPM and shaking violently. Interestingly, while I was there I heard at least two more customers having some sort of complaints with their vehicle or the service they received. Seems I am not alone...