Merging into Word (not all files)

I have a letter in word and i want to do a mail merge with information on an excel file.
the letter is regarding a receipt of payment. in the excel file i have a column (column R) titled Payment Method. The values in this column can be 'blank, Credit Card, Invoice, Incomplete'. The only rows I want to look at are the rows with 'Credit Card' filled in under the Payment Method Column. How do I include these items only?

My excel file has about 50 rows. the data I need to merge onto my word receipt is name (Column A), Address (Column B and C) and Total paid (column D) with the people that have 'Credit Card' under Column R only. The rest I don't want in my word document.

Any idea how to do this?