Inadequate Service third disappointment

I have taken the same white gold ring in 3 times to American Swiss and all the times after repairs I have have not been happy with the result, the ring firstly cracked where they did the size adjustment, I received it back on the 21st of December, and had to return back to the store because within a week because it had cracked and started to tarnish a dark grey which white gold does not do, and was told to come back at a later time as they cannot help me. on my 3rd trip to the store the manager booked the ring in and asked for the shaft to be doubled to add strength. Today when I collected my ring and i was ok with the added thickness but not 100% happy, I just didn't want it to crack again. when i got home on further inspection of my ring as it didn't feel as comfortable on my finger, I find that the top or my ring his squashed out of shape and not even, and it is obvious to the eye, i Think the only solution to this continuous problem is to have the entire ring replaced as it is my engagement ring.