Working2Hard:
Although nothing probably will go wrong, a lot can go wrong on the dives you're mentioning. I'd worry less about what the shop will let you do and more about potential issues and what you can do to mitigate them. Potential issues include:
1. Unknown buddy
2. Lack of experience
3. "Tubes" (e.g. caverns?/overhead environment?)
4. Depth
These can all cause serious problems. There are a few things you can do to lessen the issues:
One great thing you can do is hire a divemaster to accompany you on these dives. That gives you a qualified/trusty buddy and it's actually required by certain agencies if you want to exceed your training level. Anyway, a divemaster won't be a super hero that can guarantee safety, but you can be fairly assured that you'll only have to worry only about yourself screwing up and that you'll have someone around that might even be able to stop you from making a mistake or even rescue you (might).
If you don't have the cash for a divemaster, seriously consider why those limits for Open Water certs were established. I see a lot of sense behind those. I'm not sure I see why getting an AOW card automatically makes those limits go away.
I strongly advise against exceeding your training limits. Get the proper training and/or experience before going further.
Regardless of whether you're trained to go deep, you've got some other factors to contend with: Buddy Selection and Tubes.
Select your buddy very carefully. Even if they have hundreds of dives, don't be bashful in establishing dive limits (time, air, depth), communication procedures, contingency plans, how far you'll swim from one another, gear review, etc. In fact do this with anyone you ever dive with (even the divemaster!). Make them check their equipment - personally check to make sure their octo works for YOU, etc. Make sure they know how to ditch YOUR weights. DON'T BE SHY!! Buddies can be great or buddies can be a huge liability.
"Tubes" - not sure what these are, but if they're caverns, or chandaliers, or blue holes, or anything else that you swim into and don't have immediate, direct access to the surface, you've just upped the stakes big time. Now you're possibly with an unkown buddy at 90 feet in a semi-darkened place with possibly another 20-50 feet to swim sideways before you can swim upwards (to top it all off, this could be dive #13 since you only have 12 dives!
). What if your buddy runs out of air and comes over to you panicy in that scenario? I'd give that 50/50 odds for a drowning or at least a DCS hit.
Just some food for thought.
Tom