Query on service tax paid to the builder

Hi All - I booked 2 flats in a given project from builder. Builder in this case is Meerut development authority (government owned). Part Service tax is paid for both the flats. Now, 2 years later, I do not find the investment profitable and has decided to give up one of the flats.

I wanted to know if there is any provision where I can adjust service tax already paid on the cancelled flat against pending service tax on the flat I have decided to keep.

If not, is there any possibility to claim refund of service tax if flat is now cancelled. Please note that builder is refunding only the amount due to him and is claiming that service tax is already paid and therefore nothing could be done in this regard.