DUPLICATED DEBIT ORDER

MY debit order is paid every month. On 31.12.2015 my debit order was duplicated and went two times through my bank account. I only budget for debit orders that runs through my account which caused that there won`t be enough money for my debit orders. I am not in arrears and requested that the duplicated payment must be refunded.No response. I had to pay for an extra debit order, sms costs etc. I am still waiting for a refund.