LG Electronics — faulty split ac 1.5 ton

We had purchased a lg split ac 1.5 ton in november 2018 through amazon. During the winter season of 2018 it wasn't used much and when we tried to use it in summers of 2019 we found that the gas has leaked and the cooling was not happening, since it was within warranty the gas was filled on placing the complaint and we were assured that the product was not faulty and the leakage happened while the installation of the ac. The service engineer even assured us that this would not happen again. However, this year again we are facing the same issue we again contacted lg and the service engineer who visited us this time confirmed that the valve is of the outer unit is also damaged because of which gas is leaking. We have two concerns here:
1. If this was the problem why were we not told about it last year when the product was under warranty?
2. What is the guarantee that there is no other part besides the valve which is damaged, which we might discover next year.
We have been using numerous lg products for the past 12 years and this is the first time that we are facing such an issue on a brand new purchase. We are fully convinced that it is a faulty product that has been sold to us through amazon and would request you to get this replaced as the earliest. The receipt of the product is also attached with this mail. Request you to kindly look into the matter and arrange for replacement of this ac at the earliest.