Fabric Business GST query

Sir, My Client doing a Fabric business and they purchase a 100mm spares @ 18 percent for maintenance of loom fabric machineries..But output supply is @ 5 percent ... My query is. 1) Whether we carry forward Excess GST for next month any. also Input carry forward for next sales 2) R we want to Reverse the Excess purchase.. 3) Refund a Excess paid tax or Any excess portion for reversal.