BMG has warranted a lot of complaints. I think that this is because mail-order contracts are binding and can get you with tricky stipulations and mail-order transactions are also a lot more susceptible to fraud.
I have heard bad things about NCS but I can tell you from personal experiences that they are not a scam/fraud. They worked with me and listended. They were not able to settle on some of my accounts but were able to on others. And like promised my credit was cleared.
It sometimes takes some investigation and asking questions to really verify that the debt is yours, at first I did not remember doing ANY business with BMG but then I realized that they aquired Columbia House and I might have ordered one or two CD's from them a loooong time ago.
Anyways the best advice I have for you is to go through the process and be patient. Request verification and file a dispute. If you can prove that it is not yours then they are willing to close the account in other situations you just have pay in full or ask for a settlement. They were very understanding when I spoke with them on the phone and I called in a time or two to make sure they were updating my Credit and they always did in a timely manner.
I also set up an automatic withdrawal with them and they were very trustworthy. they sent me notices before they took anything and they always took the right amount and didn't take advantage of having access to my banking information. I was actually pleasantly suprised with all my interactions with them.
Have any questions let me know.