Parents had four total Verizon lines, only two of which they used for almost 8 years

Hi - My parents paid for 4 lines, two of which they never used for almost 8 years. That means they wasted almost $1,500. I spoke to Verizon twice to complain about them bilking my parents. They said they would review the account, denied the review and never called to tell my parents their request for a review had been denied. Then when I spoke to a customer service representative, they offered a $40 "courtesy credit". I realize my 70-80 year-old parents should have been more aware of their bills, but they could have shown some sensitivity and made some effort to refund at least a respectable percentage of the $1,500. Now, I'm switching them to ATT.