The California contract calls for automatic mediation when parties cannot agree on the return of a deposit. Look and see if you initialed the arbitration clause. If so, then you can also go to arbitration, but will be stuck with the arbitrator's decision. If not, you can acutally go to court and sue.
These things usually don't end up going that far. Things are said in the heat of anger that are later retracted in the cool light of day. Write a letter to escrow informing them that you want your deposit back, requesting a written response. Say as little about why you are cancelling as possible. Save that for the mediation. You can find a local mediator who is well versed in deposits. They help you set the appointment and fight for your money. You didn't say where your realtor is in all of this. Why are you not being informed and defended by that person? If you don't have one, make sure the broker for the seller gets a copy of the letter to escrow. Say as little as possible unless you have someone by your side. It is easy to accidently put your foot in it during a hot conversation with their broker. I hope someone was with you during the final walk-through who can verify the repairs were not made.
If they were made, would you still go through with the sale? Is it possible that you are getting cold feet? You may want to re-think the purchase if they make the repairs, or re-negotiate a lower price.