I have bought and am using a reserved instance however I still get monthly bills for the EBS.
Question is how do I make a similar single payment for the volume as well?
I don't thnk this is possible.
Right now, AWS doesn’t offer an option to make an advance payment.
However, some individual AWS services offer payment options that are similar to prepayment. For example, Amazon EC2 offers Reserved Instances, which allow you to pay an up-front fee to reserve capacity for your account in one-year or three-year terms. For more information about the pricing models for various AWS services, choose that service’s pricing page from the list at Cloud Services Pricing.
There is no mention here of EBS.