2004 Ford E-Series Van Gas will not go into gas tank at nor

My Ford E-350 van takes toooo long to fill with gas at the gas station. This has been an on going problem for 4 of the 5 years I have had the van. The 1st year I had it, the gas flowed into the gas tank at a normal rate then one day it just stopped taking gas at the normal flow rate. Every 1/10th to 1/4th of a gallon pumped in causes the gas pump to click off. I have tried different gas stations, pulled the black vapor recovery line back while trying to refuel, tilted the gas handle in every direction, and even slowed the flow rate of the gas going into the fuel tank and still the gas back fills the filler neck and often times back splashed at me and spills on the ground. I brought it to the dealer when it first started, they charged me $70.00, and told me they inspected the filler neck and it was clear and there was nothing wrong with it and try different gas stations which I told them I had already tried. I was forced to pay the $70.00 to get my van back and live with the problem. I called ford corperate and complained. Ford corperate said they are backing up the dealer and there is nothing futher they will do about it.

Does anyone know what to do to fix this problem without replacing the very expensive fuel tank?