My elderly friend purchased a phone through AT&T when she obtained the service.?

The cordless phone was $89 and she pays in 5 installment payments. the phone was purchased August 17. I called and was told after 30 days she could not return the phone. Why? it is not paid for. She is on Social Security and can't afford the phone. Any suggestions on how we can send this phone back and not have to pay the remaining installment. Customer service representative was rude. We have Lifelink credit which tells you how little money she has. Can anyone help? Anyone with AT&T that wants to make things right for an elderly lady trying to keep home phone service.