Actually, the advice your DCs gave you is terrible. Belief has nothing to do with dream control. Beliefs are nothing but archetypal structures, and their effectiveness depends entirely on how well defined they are. If you make up a belief on the spot, it doesn't have much power.

To get rid of annoying DCs, just ignore them into oblivion. Everything requires you attention to exist, and ignoring DCs who get in your way is by far the best way to deal with them.

Next time you want to control DCs, like when you wanted someone to kill your annoying DC, try using confidence as an emotion. The stronger you radiate that confidence or emotion, the better it will work.