Okay, several chapters have gone off to an editor, it looks promising. Now you wait. Sometimes several months. After three months you're perfectly within your rights to send the ms somewhere else. If you bother them with constant calls and letters asking when they're going to make up their mind, then chances are you won't be accepted.
Editors like to know that the authors they'll be working closely with are sane.
Believe me here. If you irritate them, or insult them, you've blown your chance. Not only with the one publisher, but if you've acted badly enough, with the entire national industry. Take to drink, eat chocolate bars until you're twice the size you used to be, but leave the editors alone for a decent period. And don't get despondent at the first rejection.