Master Listing of Vendors and banking details

First of all, i had a look at all the existing discussions on linking vendors with banking details but I still could not work out the issue that I have ...

So I would like to seek assistance from fellow users.

Aim: to get the list of vendors with site details and the bank details assigned to both Supplier level and Site level

we want to perform a cleansing of the accounts assignment; and to check and verify the banking details

Issue: We have Bank Account created and assigned to both header Supplier level as well as Site level - and each vendor may have more than 10 sites; so you can imagine the no. of records returned are massive.