Solar and gas instalation

Innovatus Energy solutions were the company we approuched to install our solar and gas stove. From the start no problems. They were on time and complete the solar instalation in 1 day - 13 October they promised to come back to supply the coc and up to date no coc supp****. Always promise to come but no shows at this stage. Then the gas instalation the same problem no coc supp**** up to date. How do you you retain your customers with this service. This is an nightmare at this stage as no insurance company will pay me out should somthing happen. What can i do????