Poor service - no COC received

Flash Gate Solar Solutions in JHB where very quick to sub-contracted Intias Solar Solutions in Somerset West to install which didn't want to leave our premises before receiving the entire amount due. Flash Gate Solar Solutions confirm that they are responsible to give us COC certificate. It's more than a week at we did not receive it. They are full of promises. What should we do now please because now we can't register of put the solar on the short term insurance.