Parking Lights,When parking lights activate, left turn signal independently stays on

When I turn on the parking lights, the left turn signal stays continually on. The turn signal light does not blink, it just stays on. This happens also when I press on the brakes. The right turn signal is working fine. I have been to the auto repair shop and they said they fixed it, but it started happening again later the same day as when they claimed they had fixed it. What do you think is causing this turn signal to activate at odd times and stay continually on?