My one month old 335i needs a new DME. Should I be concerned? What is a DME?

What is your question?

1st the door lock relay's were bad, then car was sluggish, then lost power. It's in the shop for the 2nd time (9 day's) now. Today they are programming the DME. The car only had around a 100 miles on it when I bought it brand new (paid cash)....I'm concerned about re-occuring problems in the future....I'm not technical enough to keep up with the rush and brush off answers.....I'm afraid I bought a lemon....any help you can give me to understand what the DME does and has there been any other BMW's like mine with the same problem, I'd appreciate it. Thanks....Grannie Gertz