Poor Service

I took my car (Opel Astra 2011 Model) in for repairs of Coil Pack and Tuppett cover at Reeds Bellville center on the 31/10/2019. After 9:00 am then after 12:00 pm got message saying I must come collect the car. I was shocked when I got the message because they took less than 2 hours to do the 2 things on the engine. In a space of 3-5 days when I noticed where the car was standing there was oil then I opened the bonnet of the car to look at the engine to my surprise theres oil coming out on the top of the engine where the coil pack was put in and also I noticed the engine sign showing at the dashboard of the car. I first took the car in for Diagnostic report they checked the car and found faults on the coil pack and tuppett cover No oil linking on the engine was present at the time before I took the car in at Reeds because Reeds wasn’t the first service center I took the car in, I first went to BOSCH services they didn't notice Oil linking out of the engine, they saw small things and they also confirmed the coil pack. I called the Reeds Manager Andrian W to inform him of the bad service I got but he didn't want to listen instead his telling me that theres a problem with the Turbo so my question is why didn't the Diagnostic Machine pick that up if there was a problem on the turbo and if the oil was linking at the time I took the car in for Diagnostic person who was busy with the car would have made notes to say there was oil coming out of the engine. Am really disappointed at the service I got from this Service Center.