My experiences with TAs have been frustrating. I have had to wait for days for them to get back to me with answers so I just call the cruise line myself. Fortunately, I have not had any bad experiences. Yes, I may have to call more than once but I am comfortable calling myself and I have the time since I am retired.
I see people who have had trouble with some of the reps from MSC but I have not experienced that situation. I am fortunate to have met some wonderful reps from MSC with whom I have developed great friendships. As I have said, it is an individual choice.