Is this normal, Tax Office Question, Tax Rebate?

I have just been told by the HMRC that a payable order has been sent to me, (i.e my tax rebate i have been waiting for). However, they would not tell me how much it was for, when i asked i was told "im sorry its not something i want to discuss with you".... not that they CANT, just that its something they dont WANT to discuss with me. Seems a bit odd, but under no cirstances, apparnetly for security, would they tell me the amount over the phone, just said to await the cheque, is this normal or should they be able to give the amount over the phone?