Dear K.Pratinee,
As you’ve sent invoice to issue PO , They are after the fact which you have to perform after the fact form and then procurement can issue PO ka.
We can issue PO for forward service not backward service. For the month 09 -10 , Pls send quotation or signed contract and price comparison form as required supporting documents for PO issuance.
And you require this kind of service to cover only month 10 ? I suggest to issue 1 PO to cover all required service period.
One more thing , pls ask supplier to correct Pepsi address on invoice as below