Brake Sensor problems of the 2013 Cadillac ATS

I have two issues to report that may be a safety concern: 1) there have been multiple times when driving in wet conditions (rain/snow) where I will get a 'power steering failure' warning. When this happens the power steering does one of two things. It either almost locks up and becomes extremely hard to turn the wheel, or it will still move easily, but it won't auto center when making turns. I have reported this to the dealer and they said it was a bad steering angle sensor. They replaced the sensor but the issue is not resolved and now that it's snowing it's happening more and more consistently. 2) there have been 3 cases where I was driving and coming to a stop and the car will just randomly shut down. I lose all ability to steer (since it's electric steering) and brake. This stall is different then a stall associated misuse of the clutch. The clutch has been pressed in all the way in when this happens and the car doesn't shutter like a clutch stall, just totally shuts down quietly. Luckily there has not been an accident yet, but if this happens when there are multiple cars around me it will be difficulty to avoid one.