Does anyone know how to get Uber to stop spamming my cell number?

Expressed interest in a driver's position and now it seems like that was the wrong thing to do. They have been spamming my phone number pretty heavily with text messages about their service and specials every single day, multiple times a day. I've tried calling them, texting them back, emailing them, and even using their online forms to ask them to stop spamming my number, but have heard nothing back from them.

In some way I think my rights are being violated. They are always texting me from some random number so I can't even block that. There's seemingly no kind of opt-out list I'm aware of. Is there anything else anyone can tell me to let them know I'm not interested in their service? Would it be worth my time to take them to small claims court here in California? Thanks.