Bad service - Renault SA

I visited Renault Tygervalley (I'm not giving dates because they know all the dates) informing them of the orange lights going on by my dashboard. This only happened after I've done my 75k service (I have also informed them of this). they asked me to bring in the car so that they could have a look at what the problem was (1 July 2024) I was going on holiday that day and waited for 4 hours (which I did not mind because I needed my car back). Eventually, the news came that a diagnostic was done on the car, spark plugs were removed and replaced with others and the issue (lights) was gone, with no other faults on the vehicle. The consultant told me that in the worst-case scenario if red lights come on, stop immediately and call assistance. However, they have submitted the issue with Renault SA for warranty and will provide me with feedback. Later they called me and informed me that Renault SA requested my car to be on the premises for a day or 2. Unfortunately, the vehicle can only be with you for a day as I'm using my car daily to get to work (what I said to them). So, I took in the vehicle early in the morning, the technician did as per request from Renault SA, did a diagnostic test again and and and. A few days later I received a call from the consultant to inform me that Renault SA wanted me to bring back the car (for what), the car was with your technician for a full day and everything had been looked at according to the foreman as per request.

This is the email received from the consultant:

We have received feedback from technical advising that we need to get your vehicle back to the dealership to do further diagnosis. They have not approved the replacement of the spark plugs through warranty; our foreman has provided all information motivating the replacement of the spark plugs but to no avail.

I do understand that it is frustrating for you to be back and forth to bring the vehicle to the dealership to carry out further diagnosis but that is the current outcome from technical.

I have emailed them(customer service) and the consultant a few times as well but no response.

The light is still going on by the dashboard and there's also a jerking on the car which was never there prior. This is just to inform a few of the negative experiences I've encountered not only with Renault SA but with Renault Tygervalley as well. Soon I will have to take my vehicle in for 90k service, not sure what I will encounter next.