GMC Repair: 04 Pontiac Bonn. gauges dont work right, gas gauge, temp gauge

Question
My gas gauge stopped being accurate then my temp gauge started saying overheated and burying the needle when it wasn't overheated. What do I need to fix? My mechanic thought it might be an instrument cluster? if so, where do I find one of those? thanks for your time!

Answer
We send out our IP clusters for remanufactured ones, you can check a junkyard though, it would be much cheaper, given they have tested it and it works correctly, if need be and you want the info on the company we use let me know, they are in the local detroit area not sure if they work out of state.