2019 terrain water issues

Yesterday was the second time in six monthes that my brand new terrain has had issues when we have had heavy rains. First time, we couldn’t shut the car off and couldn’t put it into gear. After many hours we were able to get it to the dealership and they unhooked battery and were able to shut the car off. After almost three days in the shop, they finally found water in a plug by the drivers side door that had somehow entered around the drivers door pillar. They said they had replaced the plug and sealed something. Yesterday we had a heavy rain storm and the service engine light came on, thr car was running like ****, could put it in gear and then it would hesitate terribly. We got it to the dealership and they said it was the same problem we had earlier. They said they found the problem and have sealed it and have kept the car overnight to let the sealant dry!!!. I am not happy as they said GM has never seen this same problem......I bought this brand new 14 monthes ago.....anyone else had this issue?