You use the same return code as if it went to a consumer account, and since it's a PPD you use all the rules for a PPD and you have the 60 days. If the non-consumer is saying it wasn't authorized, then have them sign a WSUD and sent it back.
Typically you always just go by the SEC code, and it doesn't matter what type of account. The only exception I can think of off hand is a corporate code into a consumer account and i think the return reason for that is R05 - Unauthorized Debit to a Consumer Account Using Corporate SEC Code. There are probably others, but these two are the most common I see.
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