Bad service

They phone me and say when will I pay Bur I pay every month in advance and pay bigger amount.But they told me I am in arrear The lady is rude with me on the phone when I ask her that she must look on the system to see why they say I am in arrear. How can they phone with no prove that I am arrear with my installment Can they please investigate if a person is in arrear before they phone Can they send me statements of my payment to proof that I am in arrear I am a client please handle clients in a Professional manner