Failure to honour invoice

I bought a Ford Ranger Supercab last year September from County Ford Goodwood. They invoiced me for safety belts fitted for rear seats so I could fit a child seat and a diff lock. They have failed to provide either in the last 10 months. They kept promising to attend to these items they charged me for. Now they refuse to fit them. The South African Police have opened a case of *****. I advise the public to make sure the items they pay for are already on the vehicle or it is clear you will never get them.