Really Pathetic service and cause for concern

I took my kar in for service on the 15 May 2020. I received my car back and was advised that they ordered wiperblades as they do not have stock and they would call me when it arrives. Fast forward to Monday 13 July I still havent heard anything and gave them a call. The lady said she would find out and call me back in 5 min. Fast forward again to today the 17th of July and I had to call them. I was advised that the wrong unit was ordered due to a part number. Take note that this is becoming dangerous as there are only streeks on the windscreen when wiping. The car has also been stuttering ever since I got it back with the added fact that I realised they never changed the air filter (a standard part that is changed every service and was on the invoice). I am a rep and my car is my work. If I cannot trust it or the brand it causes huge problems. I have only had the car for 7 months but these issues causes me to pause and think whether I should rather sell the car and leave the brand completely. It is not on par with the vehicles and brands I have used before.