Bad repair service

I gave my Dell laptop in for repairs at Ensure in Midrand and after 20 days I took the laptop back and demanded a payback because Ensure did nothing to repair the laptop. The responses from Ensure were vague and gave the impression that they are not interested to provide service. How can Dell recommend and authorise a company like Ensure to repair their laptops? Dell should at least check that the repair agent provides quality service but this obviously does not happen. I am considering not buying a Dell again because of this bad repair service.