I consider that a breach of contract; the shop failing to provide the opportunity to earn Rescue certification.
What does your contract say?
At the end of the day it boils down to whether or not the scuba store offered you dates THEY are available to do your checkouts. If they offered you ZERO available days THEY are available, then yes I would say you have a case.
The fact is though,if THEY offered days THEY are available, they didn't do anything wrong if YOU cannot make the dates available!
I recently got my OW certification and could not make any of the dates offered by my LDS, so I planned my own trip and found a divemaster willing to do the checkout dives.
My schedule is very hectic and I know I couldn't make any of my LDS's trips or checkout dives, that doesn't mean THEY breached their contract; it means that MY schedule was not flexible enough to work with them.
It really comes down to the following which is that you OR the LDS is fibbing a bit.
Either:
1) The LDS stated they are not available at ALL to do your checkouts in which case they lied in this thread.
2) The LDS offered you 1 or several dates of which they could do the checkout dives and YOUR schedule isn't compatible, you feel they should have worked around your schedule, and the LDS let you know that they can't work around your schedule and advised you to seek someone outside their shop to finish up.
#2 sounds like that is what actually happened, whereas you're saying #1 happened and that they didn't offer you choices of when they could do checkout dives.
Really OP, every dive shop I've looked at clearly states when and where their checkout dives are, and the burden of scheduling isn't on their end.
Recast this as an open water class. The shop offers open water training consisting of classroom sessions, pool sessions, and open water checkout dives, the cost of the open water checkout dives not included. The student is free to take the OW checkout dives with the shop, or go elsewhere for the checkout dives, and pay the additional cost somewhere else. The shop has said to the student "we have several trips a month where you can do your checkout dives", but then never has an instructor available on any of those trips to provide the OW checkouts. Has the shop met its obligation? I say "no", the shop says "yes".
Except shops don't do open water checkouts on ALL of their dives, nor are they required to.
Did they NEVER have instructors available on any of the dives they said they could finish up your rescue diver certification on?
There is a difference between offering dive trips and offering dive trips with certification to finish up classes. You're saying they NEVER had instructors available on any of THEIR dive trips to finish your Rescue diver course.
They're saying they do have instructors available but not for the dates YOU want, it's not their responsibility to cater to your scheduling requirements.
If you can't make a contracted time it isn't the LDS's responsibility to set up a dive to fit YOUR Needs.
I'm based in Maryland so I have no egg in this race.