I would like some information about a US Cellular bill my ex wife left unpaid?

Here's the deal. My cell phone was suspended on August 26th because my ex wife has an unpaid debt of 373.xx with Us Cellular. This contract was in her name only and had been for years. when I filed for divorce back in May 2013 she let the contract go unpaid and bought a cell phone on contract from walmart. On May 31,2013 I purchased a US Cellular phone & contract in my name. Also I have been having problems with the phone not working all the time since June, 2013. Today on August 28,2013 I tried to make a phone call and was told my cell phone was suspended and they connected me to an agent for US Cellular and was told I had to pay the unpaid debt left in my ex wifes name to have my cell phone turned back on. These are 2 different contracts. The unpaid one in her name and my new contract dated May 31, 2013. Now who is responsible for the unpaid contract in my ex wifes name. I feel I should not have had my cell phone suspended because of her negligence in paying her bill on her contract?