I've purchased a condo with payment terms of 20% down payment payable in 48 months and 80% balance by bank finance. Later on when I already paid for the reservation fee and 1st month payment of the 48 months, the sales agent said that It's should be 24 months not 48 months. They have policy of no refund. Can I Still get a refund of all my payments since they gave me wrong information?

A verbal agreement is binding if there is proof. You should never pay money until the terms are in writing. Unless you can prove that the original agreement was for 48 months, you may not be able to get your deposit back.

A verbal agreement is binding if there is proof. ...

Unless the statute of frauds in the particular jurisdiction indicates otherwise. In most places a statute of frauds indicates that a contract for the sale of real property is not binding unless in writing.

Also, part payment (such as in this case) may take the case "out of" the statute of frauds.

If a realtor is involved, I would guess that, contrary to OP's assumption, there is some sort of writing. OP should ask to get a copy of it.

I agree, if this is in the US, any sale of real estate has to be in writing.

A verbal contract can not be binding.

And of course you can not or should not have give money without a written contract