Notice of consumer forum to one of the Opposite party has returned stating he has relocated

I have filed a case against Hewlett Packard for delivery of defective laptop in district consumer forum. The notice of lawyer prior to filling consumer complaint has been served on the given address over bill of the seller. His counsellor has reverted as well to that notice. Meanwhile, when the issues wasn't rectified by both seller/shipper and service provider I have sought district consumer forum. The district consumer forum asked me to dispatch dossier copy of complaint to all the opposite parties along with the notice they provided. To rest of the opposite parties the notice was served/received. However with this party in discussion notice was returned. Meanwhile, somehow I found out the manager's no. of the concerned opposite party, and discussed the issue with him. He honestly admitted their office has been relocated and asked me to be on hold while he was taking his counsellor on call. Since, his counsellor wasnt available, I requested him to send me his new office address so that the notice may shall be served to the new address of the opposite party. He assured me he will text me the new address which he has not it has been over 5 days. I keep trying his number but he does not picks my call. from other numbers he does but as soon as he hears my name he hungs up. Fortunately I have all the call recordings of conversations with him. P.S. the relocated address of OP is within 1km of previous address. Therefore, my questions here are: 1. Do I need to take permission of district consumer forum to post the notice at the revised address? 2. Do I need to submit any affidavits for revision in the address of the OP? 3. What if OP does not provides me his renewed address, in such case who will be liable me or the O.P.? 4. As I have read many decisions where such petitions where rejected because of lack of proper address of the OP. However, in my case out of 3 OPs only 1 is having address issue. That to because they relocated in due course of filling the petition and its proceedings to which I was totally unaware. Pls advice course of action.