DISH NETWORK/AFNI Collection for a petty amount Skokie, Illinois

I have disconnected Dish Network around June 2010. Then they told me that I had to return the DVR etc to Houston and I have to pay $15 +tax 1.30 towards handling charges. Since I have no other choice I said OK. They sent 1 box instead of 2 and I promptly returned one DVR. Then I called them back and reported that I did not receive the second box. They sent it again and charged me another $15+tax 1.30. I refused to pay. Sometime in November I received a letter from AFNI demanding the payment. I called back in December and told that it was a double charge and should be taken out of my account. He said he will check with DNW and revert back. I received a letter around Jan 15th  stating that the payment is valid (no other details about duplicate charge) and I should pay the same and I promptly paid it on Jan 20 since I have no other option.

Today I got my credit score down by more than 50 points for the "Collection" report on my Credit Report. Till now I had an excellent credit, not even single delayed payment in last 15 years on 20+ credit cards and loan accounts. What a shame. Is there anyway to prevent this harassment. Why Credit Agencies do not hear our hues and cries. Do we need to be victims and these business hooligans. When I availed DNW, they came and instaled at my place and when I disconnect why should I return it to Houston at my expense ?. Is it not a point for a class action suit? And Credit Agencies depending on one's credit history should reject such paltry sums being reported