How to generate an usage report by customer (hierarchy)?

Hi,

I am very new to vCenter Chargeback (or vmware). I have recently been tasked to generate an usage report by customer for our Enterprise Managed Services division. I have to integrate this report to the management reporting portal and compare usage ( vCPU, Storage and RAM ) against the purchased quantity. The person generating the excess usage report was quick to generate a report in vCenter (usage report specific to a hierarchy and date range) web front end.

But I am at loss on how to generate the same report using an API call or by an SQL query. The API documentation of at the following link doesn't provide the information I need:

Documentation

Can anyone provide me some direction on how to solve the problem?

Thanks in advance,

Sudipta