For changing your MAC address, randomly generated MAC addresses are the norm unless you change your settings to use a static one. You can set up your phone to use the phone's MAC or to generate a new one every time, but by default it'll generate a MAC address per WiFi network.

As for tracking you and your internet activity, you can file a complaint with your local DPA to hopefully spur them into action, that's free. If they don't take action, or decide that your complaint won't convince a judge, you can contact a legal professional and pay them to take your case to court like with any other legal matter.