Demand payment but dont give explanation or feedback !

<p>Had a 36 month contract with netstar which ended Dec 2015. Oakhurst cancelled my contract in Dec 2015 which was also the last month of the 3 years of Netstar. Netstar continued to bill me in 2016 and was first sent a loetter from creditworx in may 2015 stating that I have been handed over. I had no previous statments from Netstar stating I owe them money. When I emailed them they said they have frozen the account and will investigate and give feedback. I am yet to recieve feedback. </p> <p> </p> <p>Today I was emailed again by creditworx stating that Netstar has yet again handed me over but never had the decency to respond to my emails or answer the queation why am I still billed after my 36 month contract has come to an end? </p>