I had the same problem with my 07. I had to replace the cluster to fix the problem. I bought a used low mileage one from eBay, and it was simple enough to install. I tried having the mileage corrected at the dealership, but they refused to help me. According to the info I have from GM our odometers can not be reprogrammed by the dealership, the dealership has to send them to the repair depot for adjustment. I have been living with the incorrect odometer and had it noted by the DMV as being incorrect mileage. The only issue I have is the oil life monitor shows dashes and can not be reset with the new cluster. I have to put the original cluster in to reset it. I think the dealership might be able to fix that issue by reprogramming the VIN info into the cluster, but I'm not sure and I don't want to pay them to figure it out.