There was this one-off British TV special I saw in the 1980?s.

It was called "How to Pick Up Girls, Win Arguments, and
Influence People."

The first segment showed a guy in a limousine, and the narrator
mentioned how you should make sure you know the chauffeur?s name
before you take a passenger.

The second segment showed an argument between two businessmen, which
was interspersed with a fencing bout.

The third segment mentioned that when making speeches you should make
demands in groups of three, and showed a clip of a speech by Hitler to
illustrate this.

Anyone know about this special and how I can get a copy?

How to Pick up Girls
US 1978  96m  Colour TVM
ABC/King-Hitzig

This is from Halliwell's Television Companion 1986 and later editions

I'm pretty sure what your refering to is an episode of the BBC science
series QED. If memory serves me right this episodes format was one of
a disembodied voice giving advice to a "man in the street" character
(possibly played by Bill Oddie but I can't be sure) on how to get on
in life. The suggestion was that the voice was the devil tempting him
into using the techniques to gain power over every one around him.