Cruise Control problems of the 2001 Chevrolet 2500

The cruise control kicked in causing rapid acceleration on icy road. The use of brakes to turn off cruise control caused the vehicle to go into a skid into left lane and towards highway median strip. I tried to steer out of the skid while tapping brakes. Vehicle went into a spin and then crossed right lane and into snow filled ditch heading towards trees. I steered away from trees, causing vehicle to slide sideways into trees and then into a chain link fence. Airbag did not deploy. I took the vehicle to the shop where they said they could not diagnose the problem unless it was happening at the time they were evaluating it. One week later the cruise kicked in by itself when I was driving at 45 mph. No rapid acceleration this time.