Diesel fuel in unleaded tank - 2006 Ford Focus

I am so mad at myself, but I recently accidentally filled the tank of my brand new 2006 Ford Focus (1,500 miles) with diesel fuel (yes the nozzle fit and it was on the same pump as the unleaded). I drove about 4 miles and my car completely stalled out.

We brought it back to dealer for repair and am hearing that the minimum for repair of this is going to be $1300.

The Ford technician just told my husband, that if what they're doing now doesn't work (I don't know the exact details), then we're getting into big dollars. What? $1300 is big dollars to me!

Has anyone but me ever done this on a newer car? Should the repair be this extensive and expensive after only driving 4 miles? I never expected this to be such an expensive error!

Do we need a second opinion?