Debt Collection Process - Is there a way to detect the authenticity of a demand letter? How would I know the existence of a law office?

Is there a way to detect the authenticity of a demand letter? How would I know the existence of a law office?

If you are in the UK, contact the Law Society on:- General enquiries: 020 7242 1222 and ask them to confirm the registered office of the Company concerned.
Do an Internet search for the firm, or a Yellow Pages search.
Heck this is an easy one. If the letter demands anything it must in all codes of law have a contact or return address clearly stated. Sometimes there is even a telephone number [do not ring it yet]. Telephone the known number for your local Law enforcement Office and give them the return listed address or telephone number in order to confirm authenticity. Be aware that an authentic name can be abused using similar addresses or occasionally similar telephone numbers. Con artists make a lot of money out of some of the fake ticket scams so you are wise to check first on all occasions.