Commercial law, litigation, contracts, IP, property law
Read your contract carefully, there are probably ways that you can escape the contract and get your deposit back. For example, does it give a date that the apartment will be finished?
I expect that there is nothing you can do to get them to build a bigger pool, nor do I believe you would be able to get a price reduction, but you may be able to void the contract. See a solicitor for assistance if you decide to go that course.