Here is the problem. You agreed to a rate which you state has an unspecified deposit and which does not state that it is refundable. You presume that this means a 25% deposit which is non-refundable and the balance which is refundable. You presume this from prior experiences.

On the worst facts possible, the property takes a 100% deposit and calls that a non-refundable rate. I am also presuming that there is nothing in the local law or rate rules which caps the deposit or makes rates refundable unless expressly non-refundable.

If the property sticks to its guns, where are you?

Forget about calling. If one call is not returned, that could be a simple error. If a second is not returned, that is intentional.

Your only real recourse is to initiate a chargeback dispute and to turn your OP above into 3-4 short declarative sentences with the backup documents clearly marked. You will have to choose your words much more carefully if you want someone at a CC issuer to seriously read this.

This forces the property's hand and either you win or lose or maybe you get a call and some negotiation.

If you win, you are done. If you lose, you still have small claims.