XYZ (Manufacturer) is making and supplying “Hanging Banner Assembly” attracting 18% GST. In the same invoice he is also charging separately, installation charges, freight charges and scaffolding charges and charging same GST rate i.e. 18%. Is it the correct way of issuing the invoice or for installation charges, freight charges and scaffolding charges he need to prepare service invoice separately with corresponding SAC Code and applicable GST Rate?