PADI requires students for many courses (OW, Rescue, Nitrox, leadership-level) to have their own set of manuals and tells instructors not to lend out materials in the interests of course quality. It is merely "recommended" for most specialty courses but PADI strongly encourages students to have their own materials.
Sounds like it's a money thing. Was the manual supposed to be included in the course fee? If so then they are trying to make more profit by not giving you what you paid for. If not, then it's your responsibility to pay for them and you can buy them on your own anywhere if your shop doesn't have them in stock.
I paid $599 (plus mandatory $119 80 in tips for the boat and crew), but wasn't told about materials being optional until two months later when I still hadn't received my cert. card. It was then I was informed about having to pass a Knowledge Review, which was then sent via email (I took a course down in the Keys). I asked about a manual, as I didn't recall some of the material being covered that was in the review (I didn't practice tying off a line or other skills I later read about in the manual). The course consisted of 8 dives (4 boat trips), with no classroom training, so everything was done on the boat. If I had known the manual was optional, I would have paid for it, because I like (need) to refer to what skills I want to practice in all my diving endeavors. However, it wasn't even mentioned that I could purchase it at an additional cost, we just ended up in a fight, and I finally got the 49 page manual. A little communication could have prevented a lot of hard feelings. Guess I'll do all my business locally from now on. Thanks for the info. ( I didn't even get the sunscreen and visor that WAS promised....lol)