Transact SQL :: Find Last Transaction Of A Particular Type For Each Customer

I am working with SQL 2012 Express and I have a table with all transactions of invoices and payments for each customer. I am looking to find the last transaction detail of either two particular types of transactions (but not both) for each customer. So far I have tried various combinations around

SELECT        MAX([sbt::dte]) OVER (PARTITION BY [sbt::code]) AS LastPayment, [sbt::folio], [sbt::typ], [sbt::net] 
FROM dbo.tblSalbatTxn
WHERE      ([sbt::typ] = 13 OR [sbt::typ] = 17) 

Then there are some cases where customers have made more than the one of the same transaction type on that same last day which I would then like to sum the net value for that day of that transaction type.

I have also worked around this but it filtered the transaction type after it found the last transaction for each customer irrespective of it's transaction type.

SELECT        TOP (100) PERCENT a.[cl::code], a.[cl::alpha], b.[sbt::folio], b.[sbt::typ]
FROM            dbo.tblSalAccounts AS a INNER JOIN
                         dbo.tblSalbatTxn AS b ON a.[cl::code] = b.[sbt::code]
WHERE        (b.[sbt::dte] =
                             (SELECT        MAX([sbt::dte]) AS Expr1
                               FROM            dbo.tblSalbatTxn
                               WHERE        (b.[sbt::typ] = 11 OR
                                                         b.[sbt::typ] = 17) AND ([sbt::code] = b.[sbt::code])))