I suggest you write the scuba business a letter demanding your money back due to a physical impairment, keep a copy and send the orignal by certified mail, return receipt requested. In the letter, give them a set period of time in which they can refund the money or advise them you will go to the authorities for assistance.
If they don't respond by the date you gave them, then go to the Attorney General's office and lodge a complaint. Do the same with the Consumer Affairs Bureau, the Better Business Bureau asking for them to get you the refund. If that doesn't work, go to your local Congressman's office and lodge a complaint and ask for help. You may also wish to go to one of the local television stations and ask them to help you. After all that pressure, the scuba company is more likely to refund your money.
If all else fails, hire a lawyer to sue them or go to Small Claims court and sue them yourself.
You may call our office at 516-248-6600 or send an email to us at Ted@Thelawteam.com. This answer does not form an attorney/client relationship with anyone and any answers do not constitute direct legal advice and should not be followed unless and until you have spoken with an attorney of your choice.
I agree with Mr. Robinson. However, I think you have a hard case. Apparently you are going to contend orally you never saw some requirement. They will deny it. It is a toss up on who the court believes.
It seems likely that the scuba company required you to sign release. I suspect that same document set out their refund policy. If not and you did not sign anything else, you have a good shot of convincing a small claims judge that you were not advised of the refund policy.