Does a C and D letter Really work?

It depends on who you sent it to. If it is one of the illegal off shore operations then they will just ignore it completely. If it is a legitimate collection agency then they will probably honor the cease comm letter since it is an fdcpa violation if you send one and they continue to call. If it is the original creditor then the FDCPA does not apply so a cease comm is not enforceable although they do have to discontinue calling your place of employment if you request it even if it is a verbal request but a written request is more effective. If you don't want a company calling you, though, I would send a cease comm just for good measure even if it is not enforceable.

I would def send it, i have found that companies have listened to it for me for the most part. once in awhile, people will pretend they never got it, but it seems to be ok. it's always worth a try.. loans are not prohibited in my state so all the companies lent to me ilgeally but even they seem to have listened (they called at first but after firmly telling them several times i will only communicate in writing, they started to back off)