I'm going to echo the responses with respect to cash or OBC rebates from many travel agencies. I think it's one of the best perks when booking through a TA. I have also read here about the difficulties people have when dealing with MSC customer service if they have an issue and need to get in touch with the line. From what I understand, it can be a train wreck.
In the future, if you decide to use a TA, look for one that has a good relationship with the line you are sailing with. Some specialize in booking with certain lines and often have direct contacts they can use and skip the on hold music and the press one, press two extravaganza. I use a large travel agency that specializes in luxury travel of all kinds. Don't be put off by their focus on luxury hotels, cruises, and resorts, though. They will work with anyone.