Who will be liable for st payment

Yes, payer of freight is liable to service tax. 75% abatement is available.

THAT MEANS WE HAVE TO PAY 10.3% OF 1250 RS ONLY. BUT SIR I WANT TO CLARIFY ONE MORE THING THAT IS WE ARE CLAIMING INPUT OF SERVICE TAX TOO WILL THAT MAKE ANY DIFFRENCE ?

Correct. Fact that you are avaling cenvat credit for input services does not alter the position. Get a declaration from the GTA that he is not claimng cenvat credit.