DRC-3 against wrong notice and acknowledged by GST dept - Goods and Services Tax - GST

Dear experts, In one of our case client purchased goods in F.Y. 2018-19. Against this purchase (bogus) client received SCN u/s 74 for the FY 2017-18 and after 20 days again a SCN of the same amount facts received for the FY 2018-19 also. Against the SCN of FY 2017-18 the client deposited only tax through DRC-03 which department acknowledged too dropped the notice . (No reply was filed by client) We filed reply for FY 2018-19 SCN but department raised demand in DRC-07 . (tax,Int,Penalty) Now the problem is that the tax as deposited for FY 2017-18 was to be deposited for FY 2018-19 the SCN of 2017-18 was to be pleaded for dropping as wrong one. Whether we can take refund of tax as deposited for fy 2017-18. Plz guide how to do that or any other recourse.