i'd suggest that you contact the letter's undersigned and/or other contact info on the letter to find out more.

no point contacting tmpoint cos the issue have gone up to HQ level, probably debt management dept.

also, i'd highly recommend that you make a police report complaining the unwarranted letter of demand from the TM's lawyer and provide all necessary evidence.

The lawyer's will back off and examine your case carefully IF you show them your police report and supporting evidence.