Can't unlock certain characters for multiplayer?

So when me3 came out, I spent a lot of time playing multiplayer and unlocked most characters pretty fast. After the second multiplayer DLC released and I  had unlocked everything except the salarian engineer (which is rediculous as it's supposedly an uncommon unlock) , I asked ea help if there was some sort of glitch stopping me from unlocking the salarian engineer. They said "Don't worry about that." and I unlocked it in the next pack I purchased.

I'm having the same sort of problem with the N7 Destroyer and N7 Slayer. I contacted help again and they told me to come here. So I'm just wondering if anyone else has had this problem, and if anybody has found a solution (whether you have to talk to ea help until they help you, or if you just have to wait it out) or if there's even a glitch at all. Maybe I'm just really unlucky?