Intermittently the key will not turn in the ignition.

The key will not turn the ignition. First thought was the key had gone bad, so I used the new key. No change. I took it to the Toyota repair shop twice. First time the service manager said it was because the steering wheel was locked. I disagreed because the steering wheel had not locked once in the year since I purchased the vehicle. The service manager forced the steering wheel to lock and showed me that the ignition was locked. He had to practically turn the car over to get it to lock. Next time I took it in for the same problem and was told that the battery was low and this could cause the problem, that Toyotas do funny things when the battery is low. Battery replaced. Problem continues. This last time, three weeks ago, the steering wheel was free wheeling the entire time I tried to make the key turn. Sometimes letting the vecicle sit for a while frees up whatever is stuck. This is dangerous in an emergency situation.