Lifeline review: Billing / bad service

I was a customer for 16 years through Phillips. Over the past few months, I noticed my fall detection wasn't working correctly. Also, when I placed a button call it took 3 or 4 minutes for someone to come on to check on me. I had a TIA last year, so my medical alert is very important to me. Over the past 16 years I have not missed a payment to the company. One day I got a message from Lifeline that my payment was past due and they were going to disable my button. I talked to billing and told them the bank had sent the payment. My bank offered to provide proof of payment. When I started receiving terrible service, I decided it was too important for me to not change. I changed to another medical alert company. I called Lifeline on Nov 8th and told them I was cancelling because of the billing issues as well as the bad service I was getting. When I cancelled, I was told they would send a return label asap. I did not get the label until the 21st, two weeks later. I immediately returned the device. I then got a bill for the time I was not getting service. I called billing about the bill and she said it would be about 30 days before the bill was zeroed out. I now have another bill for TWO months of service that I have not received. I am a 79 yr old widow with heart disease and other health problems. I am at a loss for where to turn with this problem. I do not know who regulates this company (i.e., FCC?) so don't know what to do. I need help.