Help with a movie name

My friends are trying to remember the name of a movie, it sounds vaguely familiar but I haven’t a clue.

All they can remember is a guy rescues or finds a girl (possibly under the kitchen sink) and at some point he hides her in a boarding school, she says you will keep in touch, he says yeah of course (or words along those lines) and she slips a mobile phone in to his pocket as she knows he doesn’t have one.

any help appreciated.