Unnecessary delays and slow service

My car is at the pannelbeater from Tuesday 17 Feb. The damage was assessed at their premises (by a person on their employ or resident at their area/premises). The car is a Ford Fiesta, with standard parts available from dealers within 1 km radius from the workshop. The repair authorisation was given by the insurer on Monday 23 Feb at 10h00. Off the shelf parts are only expected to arrive on Fri 27 Feb, a full 5 days later, and as they do not work weekends, one full week to order parts that I can purchase in one day!!! No wonder that Proline quotes 3 weeks for the repairs. Two weeks to get going and a couple of days to complete the job! Are they in collussion with the insurers to force the customer to take additional insurance for a replacement car in case of accident? In the meantime, with the insurers' delay in approving and the time to repair the car, I am without one for one full month. This is slopy service and is not acceptable for a firm that advertises itself in their brochures as follows: Why is Proline your repairer of choice? Good question!