AT&T refuses me DSL service until I cancel current provider

Here is my situation. I have basic phone service with AT&T. That's it, nothing else. I have DSL service through Earthlink. I placed an order with AT&T for DSL service. My intentions were to cancel my Earthlink service after I received equipment from AT&T and verified my service was working. AT&T refuses to place my order until I cancel my existing Earthlink service. Not setup a cancel date in the future, but immediately discontinue my service. Leaving me without internet. I asked the AT&T rep, "how will you know when I cancel my service". She said "we'll just know". I ask, "how long after I cancel will your system be notified". She says "I'm not sure. Maybe a few days. Maybe a week". That is crazy. AT&T is asking me to cancel my only internet connection, wait up to a week before I can even place an order for service. And then wait a few more days for equipment to arrive. This could leave me off line for a couple of weeks. How is that feasible? I'm trying to move my business to AT&T! Why in the world won't they take it?

Does anyone understand what is going on? I've called a few times and spent multiple hours talking to reps and supervisors. They all just repeat the same mantra. "You must cancel your existing service. You must cancel your existing service"