2005 Chevy Caprice

Hey, I'm new here and I have a problem with my 2005 caprice.

I had a 60K service done a week ago, and then
driving home from work yesterday my 3 window cluster showed the following messages:
1 - Service Vehicle Soon
2 - Safety Mode - Reduced Performance

I am not worried about 1 as I will get Holden to delete this cause the service has been carried out.

I am concerned about 2. Not only the message, but the fact that when this came on, I basically could not go above 80kmh. I would put my foot down, and the car would down shift to 2nd, but not really go.

Does anyone know what this fault is, and more importantly, how I can get rid of it so I can drive he car normally?

Thanks