VW Polo Engine keeps cutting out

This is re: a VW Polo not a Golf.

Everytime I drive at slow speeds in my Polo e.g. when I am in traffic or at traffic lights or parking, the battery light comes on and the engine cuts out completely. I then have to restart the car. This keeps happening until I have gathered enough speed. The exhaust emissions light comes on and goes off at random, as does the EPC light.

I have had 2 diagnostic checks done on the car, as well as recently getting a full service and MOT, but everything is in order. The alternator / battery have also been checked. I have no idea what it is, can anyone help?