Definately go through the retention Dept. but be warned, they can be somewhat argumentive and difficult.
Last Oct/Nov I kept losing my local channels and half of my other channels (we were on a 2 dish setup). I called, got the run-around from every department, being told they were upgrading me to 1 dish, etc etc. I finally got a tech to come out. He shows up late, does a crap job and when I look out in the back yard it looks like a yard sale was taking place. Satellite junk and trash everywhere, and the work he did was absolutey horrendous. It turns out that he didnt even fix the problem! I call up Dtv again, go round and round with them over a 2 week period, unable to get anyone to do anything. I eventually get a a tech that tells me on the phone that it wasn't the techs fault, that DTV was covering up for spotty reception issues. I have a customer service guy argue with me, and I got hung up on by 2 different retention people and transferred to the wrong dept 4 times. I finally get a tech supervisor out to the house, he promises to fix it within 4 days. Two weeks later nobody knows anything and there still wasnt a tech at my house. After that I went through a lot more passing of the buck until I finally get someone sympathetic at dtv who tells me about the retention dept and the conflict resolution dept. I end up taking pictures, sending them to Conflict resolution & the technical installation company before I get anywhere. It turns out that it was a combination of the DVR dying, the initial install ('06 install) being botched, and the tech that came out for the service call not having a clue what he was doing.
In the end I was given a $150 credit for the 1 1/2 months I had spotty reception, 6 months free Showtime, 6 months free HD, $10 off my bill for a year, a FREE HDDVR, and a free complete re-install including being upgraded from 2 dishes to 1 slimline dish installed where I wanted it installed. I was finally happy when it was done, though the 1-1/2 months of hell were definately enough to have me calling Dish, in fact I told the retention dept that I had dish on the other line at one point and I was going to sign up with dish.