Dell India — dell inspiron 5559 laptop

I purchased a dell inspiron 5559 laptop with service tag: 59bk662 on 14-8-17 from dell exclusive dealer paras computers at thillai nagar trichy. While purchasing, the sale consultant, informed that he would provide the dc and the invoice shall be sent by e-mail. Based on this assurance i have made full cash payment and received the above lap top. How ever, the invoice is yet to be received even after several follow up with the above person. Also the warranty status in the dell website indicates warranty coverage up to 22nd march 2018 only where as it should be up to 13th august 18. I raised this issue through online complaint to dell for which dell has not cared to respond.