A ~ is a method of selling in which the salesperson puts a lot of pressure on someone to make them buy something.
...a double-glazing firm whose hard-sell techniques were exposed by a consumer programme.
N-SING: oft N n
HARD SELL
Meaning of HARD SELL in English
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012