No refund can be claim , Infact as per the Provisions of Anti-profiteering measures - Section 171 of the CGST Act, 2017:
In terms of Section 171(1) of the CGST Act, 2017, 'Any reduction in rate of tax on any supply of goods or services or the benefit of input tax credit shall be passed on to the recipient by way of commensurate reduction in prices.”