Answer:
WFN = World Financial Network National Bank
PBP = Pay By Phone
This can occur from paying a store credit card w/ your debit card or using an online billpay service. Alot of stores don't own there own credit or use a 3rd party to handle of the credit. (Example: you pay your Bobs Store Credit Card, but BSCC doesn't process there own credit, it's handled by Mary's Credit Service, so instead of BSCC being on your statement MCS would be on the statement.) so WFN is probably just the person that the card is run through. but if you have a dispute with it you could contact your bank.
Check the amount of the withdrawl against any payments or purchases your recently made, and you will likely find your answer. Look especially at department or specialty stores where you have recently paid the bill online.