A hammer drill would be your best friend with this project. It could help you break up the concrete car stop and remove crumbling mortar between the flagstone. If thats out of budget a big sledge hammer should be able to break up the stop and a cold chisel and small sledge the mortar/concrete joints.

you will then have to pull out or cut off rebar that is probably holding your car stop in place once you have broken it up. A metal cutting blade on a recipricating saw would do that or a hacksaw. Then you could redo the concrete/mortar joints between flagstone or just use sand. At least thats the way I would do it:)

Thanks so much! I will definitely check it out.

The other thing that stinks is the car park hangs overhead and the rain water comes down from the left without and pools to the right. It had rotted stairs attached. We put in a ramp, now I worry the same will happen.

We used silicone on the bottom to help some but it will not stop the rain run off. That has also damaged the flagstone to the point it is. Go figure

Re direct the rain run off