There is a catch here that nobody is thinking about.
Remember that competition you entered, or the 10% off voucher you wanted so you put your contact details into the little pop-up and ticked the box saying you read the terms and conditions? You likely not only gave that company, but also all of their affiliates, partners and other loosely associated entities permission to call you. So the moment they get taken to court, they will just produce that record and be done with it.
Sure, there will be exceptions but the courts are already years behind on more urgent matters so don't expect to see any real change soon.
Only way to fight this is to make them waste their time. stall ,reschedule appointments, ask for more info, waste as much of their time as you can until it become unprofitable to contact you.