Public use of Hall private Car park

We currently have problems with non- hall users parking their cars in the hall car park overnight and during the day. Politely reminding them that they should not park there, has no affect. One solution is to charge  non- hall users to park their cars. However I suspect this has many pitfalls, if any halls have experience of charging for parking or can give advice we would welcome it

Regards

Ron Cabble Mosterton Village Hall