Was it wrong what maria and toby did to Malvolio?

Malvolio, a self described pious man, is in love with Olivia. Of course this provides great entertainment for other characters. Maria composes a letter in Olivia's handwriting, and leaves it so Malvolio will find it. The letter convinces Malvolio that Olivia loves him. The letter a gets Malvolio smile, wear yellow stockings and cross garters (everything that Olivia despises). After this Maria, Toby and company lock Malvolio in a dark room. By this time Malvolio is acting so strange that Olivia decides he is possessed with evil spirits.