No cooling off period allowed

I app**** to increase my overdraft. Yesterday they called to say I had been approved for more than I app**** for and wanted to know how much I wanted. I told them over the phone but had no time to think about it as they wanted an answer immediately. They put the limit in place and afterwards I had time to think about it and wanted to change my decision. I was told I can't undo a decision I made just yesterday. Also, I have received nothing in writing to confirm the terms of this new arrangement and I have not signed anything. My feeling is that one day later I should still be able to change my decision. Do I not get a cooling off period in terms of Consumer Protection Act?