Nissan Worcester not up to scratch!

My wife's Nissan Qashqai 1.5dCi went in for its 45000km service at Nissan Worcester without any problems. After the service we heard two noises that the engine didn't make before the service. I even had to ask them for the service report, it wasn't given to me of left in the service booklet like it's normally done. The car went back three times and they still couldn't figure it out. I sat with the service manager and one of the workshop guys in the car while the car made the noises, but shockingly they couldn't hear a ting...! After the third time i contacted them to let them know i'm still not satisfied, even my 5 year old daughter can pin point every time the car starts making the noise. Worcester Nissan was suppose to contact me last Tuesday, but no one contacted me! The car is not going back to them for service again. Will try and find another dealer to check and service the car, because we sit with the problem and who is going to buy a car that makes noises that's not suppose to be there? Never mind if it's harmful to the car or not!