I have Hampton Bay 54" fan MOdel 523 127. The fan speed is always full on and can't be stopped or slowed down. The light control won't turn off the light unless I turn off power and then back on. Where's the problem: in trasmitter or receiver? I've changed the batteries in they are in correctly.

It sounds like you may have a receiver problem. See if this helps

Troubleshooting Ceiling Fan Receivers (http://www.ceiling-fan-brands.com/ceiling-fan-remote-and-receiver-problems.php)