Aside from the information posted in this forum about revoking authorization, there is a way to stop PDLs without having to deal with them. Every PDL uses an ACH Processor, the entity that actually sends their credit and debit files at the end of the day. The processor can be found be contacting your bank about a previous ACH and simply asking them where it came from. This is different from the obvious "who" it came from. They will be able to identify the institution that sent the file your ACH was included in.