Am i unlucky or is car tinting that difficult?

Hello. While ago my mother bought camry and had outside tinting shop to do tint for her car. After awhile the rear windshield tint started peeling off causing unsighty bubbles. So, she had the tinting removed. But in the process, they messed up that defrost line thing and defrosting stopping working properly afterward.

Now I bought honda accord 3 wks ago. I paid $600 to dealer(which is 2-3 times more expensive that outside shop) to have it tinted thinking they would do better job. But, after tinting, my car started making annoying rattling noise when driving. I brought the car to service department and it turned out tint on rear windshield was peeling off from bottom and making that noise. They said they have to peel is off and do it all over. But, the tinting tech is not there everyday and I have to wait. They gave me option to just come back when tech comes. But, i decided to leave my car there. So, it has been like 3 wks since I purchased the car and my car is still in the dealer.

Is it common? I thought tinting is commonly done properly and what happened to my mom is exception but it seems it is not. Is tinting that complicated and technique sensitive? Since they have to peel it off, will that most likely mess up defroster on rear windshield? I regret that I decided to put tinting.

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