Broken broken aircon pump pulley + dual mass crank pulley

[Bluecatcottage]

Has this happened to anyone else? It happened to me yesterday as I was driving down a steep hill, there was a loud bang under the bonnet and the red battery light came on. I couldn't pull over immediately and then there was a second loud bang and the red temperature light came on. I was able to pull over and the pulleys were shattered, belt broken and bits were everywhere. My Yaris is 5.5 years old with 65k miles on the clock. Any idea how much this will cost to fix?