Billing and Customer Service Staff

I paid a 2 year subscription to Good Housekeeping which expires in August 2016, which is why I was wondering why I kept receiving an account termination notice. I wrote them a letter on Feb 15,2016 giving them the check number of my paid subscription and when my subscription expires but I kept on receiving this unpaid notices . I called their customer service office and the person I spoke too was not very helpful, I gave him my account information but he kept on insisting to give him my e-mail address because he needs it before he can help me.  I told him it was not relevant but after I gave it to him he was still not able to help me, instead he told me that his supervisor will call me back and hung up without getting my phone number.  I have an outstanding credit, I don't want this to affect my status