Ford Repair: General Repairs, gas tanks, electrical loads

Question
We have an 1991 E350 Van with a 460 and I think the C4 transmission with the planetary overdrive unit.  We took it to our local dealer because the battery was not keeping a charge and one of the gas tanks was not feeding. They called today and said they found nothing wrong with the battery or alternator, but when the tech took it on a test drive to check out our "loss of power" he blew up the transmission.  I was awestruck.  We replaced the tranny in 2001 with a new unit.  We have less than 50k on this new tranny.  The dealer is telling me that it could have happened at any time, and that it was just unfortunate that it happened to the tech.  I don't know what to think.  Do I have any ground to stand on to ask them to cover half the tranny rebuild?  And further if the battery and alternator are fine, why do we keep having to jump start it every two days?

Answer
Hello and thanks for the question...I'll try to help.
 The first part of your question I will not answer.......I'm a mechanic, not a lawyer.
As far as the battery draining.......make sure that all electrical loads are off when leaving the vehicle.
Hope this helps,
Erik