Can a concrete driveway that has been sealed have the sealer somehow removed? The customer believes that the sealer is causing the paint to peel.
They do seem to make solvents that can remove the sealer. You should be able to find something at your local home improvement store. It's not going to be easy and the chemicals are nasty, so you would want to be careful about harming plants if any are along the driveway. From a quick reading of some people's experiences online, it looks like it's a lot of work.