Bad after sales service

I purchased a used vehicle at the end of August 2018 from Imperial Isuzu Isando. The salesman was Michael Tsheola. On delivery he notified me that the service book had been misplaced and a new one will need to be ordered and stamped. It is now 8 months later and I am still waiting for the book to be delivered to me. I have sent numerous emails, most which I receive no response when I chase up. I need this escalated and sorted out ASAP.