Engine Problem_Renault Megane

I bought my car on 31 May 2013 as a brand new car. I have been servicing my car regularly & it's never been involved in an accident with my latest service interval being 27/11/2017. However, on 07/12/2017 my car started Jerking & displaying some warning signs on the dashboard. I immediately took the it to Renault Paarden Eiland, wherein I was advised that I leave it so that they can have it checked the following day.

On the following day, 08/12/2017 they called to inform me that the car engine needs to be diagnosed, but in order to do that they have to strip the engine. However, they informed me that the cost for this job will be R7000, thus I needed to first commit that I will pay it in case the claim is declined by warranty. To this, I asked "why would they decline it because the car is still under warranty". They advised that if my car was ever involved in an accident then they will decline the cover. Knowing that my car was never involved in an accident, I advised them that they can go ahead with the job.

I then asked them for a courtesy car, but they advised that "only after the warranty has approved that, I will get a courtesy car". From that day, they never called to update me on the progress of my car nor taking my calls. On 13/12/2017, I decided to physically go there & only then I was informed that the engine has been stripped and the cylinder taken to another company for diagnosis. I then complained about not being updated on the progress of my car & that they are not taking my calls. They apologized and assured me that they will keep me up to date on daily basis, even if it's by SMS,s.

They then called me on Friday 15/12/17 and advised that the cylinder will be delivered to them on Monday 18/12/2017 & they will send a claim to warranty on the same day, however, it takes about three days for the warranty to get back to them with the feedback Furthermore, after the warranty has approved, it will take another ten days for the car to be fixed.

Now, it's been almost three weeks now that my car has been with them and to make the matters worse, I have lost a lot of business because I do not have a car to go & see my clients & contrary to their assurance, they have not contacted me with the feedback ever since Friday 15/12/2017.

Please help