You need to contact your local council since you can try to solve this using two different routes which both involve the council. The first is that she is running a business from home in breach of planning regulations, whilst she thinks that the council cannot stop her they may feel otherwise.
Secondly you need to speak to the environmental health department since even assuming she cannot be stopped from running the business the level of noise is unacceptable and assuming it is too high the council can stop her from having the speed ball sessions. The council will come and monitor the noise level whilst a speed ball session is taking place.
I hope this helps. If I have missed something or you have further questions please reply