I think most of the enterprises/medium businesses I deal with don't even have contracts with Lenovo at all. Mostly just Dell and HP, and depending on the type of work a lot of Apple too.
My spouse's employer just decided to kill its Dell contract for laptops and go with ThinkPads because Dell's warranty service is so limited/shoddy, and the reason cited is actually a common story. There are more Lenovo enterprise contracts than you think, and those that still use Dell aren't measuring all the costs or are getting very, very special deals.