former employee's rights against former employer regarding unpaid cell phone bill, WA employment and contract law

payment of cell phone bill: my wife was required to obtain a cell phone from her employer back in 2004 which she did. They agreed to pay the bill which they did. She left the business 2 years later and was asked to leave the phone with the new manager which she did. for 2 and 1/2 years they used and paid the bill as they always had. then suddenly we get a call from the bill collector saying we owe over 600.00 for past due account. the phone was still in her name and so mafter the company quit paying it came back to her. yes she should have canceled and told them to get their own phone after she left but did not. The owner says tough it is in your name you pay it whcih we could do however it is the principal that we are getting screwed. what are you thoughts? thanks - Is this your question? Add additional information