Litigation. Downside is it could drag out for a while and require spending more money now. Unless you can find an attorney to take the case on contingency, which seems a long-shot. Even if you win, likely won't get attorney fees back. Depending on the amount of money involved, may be better to cut your losses.

Replacing with used or reconditioned parts is common even for a new vehicle warranty repair. On the bright side, since the dealer has replaced parts, that clearly shows they know the car has issues. Keep pressing the dealer. Eventually they may get the car into reasonable drivable condition or offer to trade it for something else.

If all else fails, contact the local news media. It's a hail Mary, but sometimes gets results.