Obviously you either work for a phone carrier or Verizon because I don't know anyone that would be ok with being told they would have a bill significantly cheaper than what the actual amount is.
I expect people to read everything in front of them and double checking no matter what carrier. It is some thing that has been said by numerous people who have never worked for any carrier will tell you. The FTC, and a Lawyer will tell you also. Ever heard the old saying "Get it in writing?" Tried and true advice that has been around for decades long before carriers were around. Shoot Verizon God awful receipt they give you is everything in writing which you could have spent 5 minutes to see everything and also if there is a discrepancy easily could have gotten fixed right then and there.