waiting ages for a refund, empty promises

Poor service. Requested a settlement letter, and settled the amount before the stipulated date (28 April). MFC proceeded to take another debit order on 1 May, even though the account was settled. I have been enquiring about a refund since then with no success, 9 days later and no closer (9 May). It keeps getting referred to another staff member but nothing gets actioned, and no one calls back as they promise to do so.