Bad service

I have paid up my account a debit order still off my bank account. I call and the lady i spoke to said it takes 24hr to do a refund. A few days later i called again and was told that they require proof of payment when i asked the lady if she cannot see the account is paid up she said yes but they still need proof that i paid the account up and the refund will take up to 7 days before they can do it. My question is why must i provide proof that the account is paid up when they can see on their system its paid up. This is the worst service ever