Nell is mad that her current flame is going on a buisness trip with another woman, so she leaves him a message on his answering machine, and then gets second thoughts about it, and forces Samantha and Joey to help her go to his apartment and erase the message.
Gimme a Break! S04E15 (“The Answering Machine”) first aired on January 12, 1985.
In the US, Gimme a Break! season 4 — including this episode — is available on The Roku Channel.