Yes, I recently had to use the CCCS and they were very helpful, I was made redundant and couldn't afford to pay my full loan repayments. The bank didn't really want to listen, even though I made a reasonable offer, so I went ahead and spoke to the CCCS and they helped me sort everything out with template letters, phone calls, etc. I now pay a token amount until I can afford more, the only thing I get is a letter every so often from the bank telling me that I am in arrears, but as they're legally obliged (I think) to do this, it doesn't feel like harassment. Also, that particular bank decided that, after over twenty years of having a shining credit record and various accounts with them, that they'd no longer be doing business with me and closed my account.
To anyone struggling, and I mean really struggling, the CCCS is the best starting place. It seems that banks suddenly sit up and listen when these guys get involved.
The only thing I'm still unsure on is how badly this will affect my credit rating for the future, but as there was no other way out, that at the time was a minor concern.