I would argue that it's not very convenient if they can't fix the problem correctly and cause more issues with each visit.
I have a great salesperson at the local dealer who knows me. I just call and tell him what I want and he gets it one way or the other. He knows I use X plan. But their service department screwed up twice in a row so now I refuse to do business with them.
It's like my wife's grandmother used to say about her Curtis Mathes tv. After it died for the 5th time and they came out and fixed it I asked her why she kept buying Curtis Mathes tvs? She said because when they break they come out to the house and fix it. I said well what if you bought a different brand that never failed in the first place? It took her a few minutes to get it.
Some good points to ponder for sure, thanks. I too had a Curtis Mathes (never broke). Like I said as long as the MKX is fixed under warranty I have had patience with the work being done. I won't be any longer. I thought for the knowledge of the forum I would post my experiences. For what it is worth I used to lease cars for my business and I have personally owned 17 cars. Loved leasing because after 2 or 3 years tops you got rid of the car, good bad or indifferent. I only kept one car - an Accord which I sold to my daughter. But I kept the MB for 157,000 miles so that says a lot about the quality and reliability of that car.