Sorry to hear that you’ve had so many problems. I bought one of my daughters a new i20 Ultimate privately nearly 3 years ago and apart from a couple of minor issues, sorted under warranty, it’s been fault free. It sounds as those yours was a Friday built one!
Can I ask what was done under the warranty? Heated steering wheels are an acquired taste, but I absolutely love mine and would be gutted if I had to say good Ute to the feature.
There was a rattle / vibration coming from the drivers door pocket. Also, one day my daughter couldn’t restart the car after stopping at a supermarket but after leaving it for half an hour she managed to start it. We took it to the dealership and they couldn’t find a fault. Thankfully it hasn’t done it again since (that was over a year ago). Other than that the car has been fault free, as was her previous generation i20 which she had for over 6 years from new.