Carpet cleaning firms - need some recommendations please

[Rollerball]

My mother lives in North Somerset and needs her plain living room carpet professionally cleaned. I've thought of hiring something like the Rug Doctor and doing it for her, but to be honest I think that a professional would do a far better job than I could.

But how do I find a good firm to do the job? Are there any 'standards bodies' that carpet cleaning firms adhere to?

Can anyone advise please?

Thanks

Edit:

Just stumbled across the National Carpet Cleaners Association:

http://www.ncca.co.uk/

Are they a good, reputable body?