Verizon has begun sending text messages with instructions on how to redeem a $20 account credit for last week's nationwide wireless outage. The message states that the $20 credit is intended to cover multiple days of service and apologizes for the outage. "Valued Verizon Customer - We let you down this week. For that we are truly sorry. We would like to extend you a $20 account credit that can be easily redeemed via the link below," reads the Verizon text message. "On average, this covers multiple days of service. This credit isn't meant to make up for what happened. But it's a way of acknowledging your time and showing that this matters to us." The text message also tells customers who are still experiencing connectivity issues to restart their devices and includes a link to access the…