CREDIT ON EXCESS RATE OF MRP IN GST

sandeep saini (40 Points)

29 August 2017  
if i sale a product which MRP is 100rs before Gst ,And after GST this MRP is 120 But printed MRP IS 100 rs on product ,i can not sale this excess MRP. therefore i loss tax on 20 rs ,, please give me solution of this is compnay not give this credit and not disclose new MRP in newspaper?