When you reach the automated response system, you will be asked to say or enter your account number. You can use the number on your card. Additionally you will be presented with an option to get information in Spanish (press 2). For security reason you may be asked to say the date of your birthday. The system will locate your account and announce your rewards balance.
Then you will be prompted with the following options "Repeat", "Redeem Rewards" or "Representative". Say "Representative" or press 0 to speak with a Capital One Rewards agent.
You can also check your rewards online by logging into your Capital One account.