It's like the next level in support.

Like level 1 handles username and password crap. Making sure they typed everything right. Looking for common crap.

Level 2 is looking more into settings and more detail of what the problem is. Again looking for common things.

Level 3 is even deeper. People that have extensive 1st hand experiance with the product. Possibly helped beta test it.

Level 4 is developer level (usually). The people that actually made the product. Research and Design. If they can't fix it, no one can.

Level 5 is the refund department j/k... some companies spread it out over 8 levels... some have it only in 2 levels. But you should get the idea.