Unreliable electrical engineer

Performed work installing an inverter system for us. Not once arrived when he said he would with no communication on running 3+ hours late, initial work had to be redone as following installation mains was not working and I was only able to run off battery power. While work was completed and paid for, I have still not received my CoC after more than a month of waiting and repeated requests that it be provided. Attempts to contact telephonically, through email, WhatsApp and sms goes ignored and unanswered