Tds deducted in amc

dear sir, I m work in Hitachi air conditioning company... my query is that.. if we given amc contract to our company.. like a.... Who work for govt department.. they have ac in their House... we take amc of their AC... they deduct TDS of 2% from gross value after discount... I want ask how they deduct... tds... 2%...When tds is not there in GST... plz tell..