I've done the TPS business but to no avail.
If you get to speak to a person, try this.
Ask them if they are aware of their legal obligations under the Data Protection Act. Applies to any company calling on behalf of one in the UK.
Odds on they'll answer yes.
Ask are they aware of the outcome of not complying with the act. That is a £5000 pound fine for the company and the person who made/ or took the call if they tell you its an automated system.
The information has to be correct, up to date and they must have the permission of the person,you, to use that information. If that information is incorrect, then by law, their database should not be used any further until it has been checked and any errors found corrected.
At this point you'll have them worried enough to either drop the call or push their luck a bit further.
The latter is easily countered by asking to speak to their Data Manager/Controller who has placed them in this position. This so you can lodge a complaint over their database being incorrect. Again its a legal requirement.
Did the above to a company(mobile phone deals) in Leeds and they were wary when such a level was reached. Trip made out their way later that week. I had a clear view of their offices & carpark. Informed them again of what would happen if they continued to call, when a recovery vehicle entered the carpark. I simply instructed them to take a look out of their window towards their cars, as I'd arranged to have a few removed, legally, as a result of their continued misuse of my information. The rush to get the cars away was worth seeing.