It cannot be stressed enough what LAT and Eric said. That guy is trying to rip you off and take your money. Run as far away from that shop as you can. For future reference: Most certifying agencies (NAUI, PADI, SDI/TDI) accept the certs of other agencies. Meaning, if you get PADI OW certified and move somewhere that is NAUI or SDI, they will recognize the PADI OW and help you get into AOW WITHOUT having to recertify as Open Water. That crap your shop is trying is nothing but a scam. You could do others a favor by posting the name of the shop and instructor.