$540 via promo credit when you add a new smartphone line with your own 4G/5G smartphone on postpaid Unlimited Plus plan between 5/18/23 - 5/31/23 & port-in req'd. Promo credit applied over 36 months; promo credits end if eligibility requirements are no longer met.
Try removing your SIM and re inserting it. Then try to reset network settings. Go into Settings > Search "Network" at the top > Tap on Reset Network Settings > Tap on Reset Network Settings again. Warning this will remove all your saved Wi-Fi networks. That is where I'd suggest to start.