The reply posted to this post earlier (the long post) with tips on how to gain more exposure and increase chances of promotion/raise CEP are pretty spot-on. To summarise, don't just do work assigned, instead ask for some CCAs as well, and most importantly, be SEEN to do work as well. From personal experience, visibility of work done is just as important as doing the work well (though I have to admit I myself have been guilty of being just focused on completing the task at hand)

I haven't dealt with the salary stagnation scenario yet, but I have some friends who are in that situation. Have one friend in early-40s who has been in that position for 3 years now, stuck at MX11A. His approach is to be zen about the whole situation since he is very comfortable with what he earns vs what he spends (also helps that he is single).

Salary stagnation is usually due to CEP-related issues. So, the only way to overcome is to do stuff that raises CEP, which then puts you in a good position to be promoted. Otherwise, as I have suggested before, 2C+ puts you the promotion queue, but in a low CEP situation, even 2B+ won't help your case. I know of someone who has had B+ for 3-4 years in a row and still hasn't been promoted (recently stuck with salary stagnation issues because those pay increments add up quick).

Lastly, I doubt furthering studies will help increase your CEP - unless its a case of being sponsored to further studies by your organisation. However, it could be a good way to gain new skills or improve your chances to land another job (e.g. if you did an MBA/MPA).