Bests & Worsts Reviews from Amazon

I followed their online product guide and selected the GB70 to start my Dodge 5.9 liter truck. Their product guide and their description right here on Amazon states this is the correct unit for up to a 6-liter diesel engine. Dead batteries on 5.9L diesel truck. Connect fully charged GB70. I get one little half-second "ugh" as the truck turns over - then nothing. GB70 battery level is now at 25%. That's it - it's out of juice. I called their support line and they said it should have worked because the GB70 is the correct unit for my vehicle. I mentioned I had two batteries and they said: "oh no - none of our units are designed for two batteries". I said "but your web site says it's designed for a 6 liter diesel and I don't think there's a 6 liter made that doesn't have two batteries - I'm positive there's no Dodge Cummins 5.9 that doesn't have two batteries". They said, "they will check with their web admins to get that information corrected." I said I checked with Batteries Plus before I ordered and the product guides they send to their dealers also say this is the correct device for up to a 6L diesel so it's not an error on the web service. It's an error in what the product is being sold to do. Then they said: "we recommend you buy our next larger size to work around the dual battery problem". Wait, "you just said none of your units are made to work with a two-battery system Now you say I should just buy one size larger and it will work? If none of your devices will work with a dual battery system and even the one rated for a 6-liter diesel won't start a 5.9 then where did you get the information that I should scrap the $180 unit that you recommended I buy and spend $300+ more to get a bigger one that you just said won't work because none of your devices will work with a dual battery!?" It's crazy. "We told you this is the right product. You bought it for $180. We know that our product won't work because none are designed to work with dual batteries, so send us another $300+ bucks to buy a bigger one that we just told you won't work either" If I had bought the $300 in the first place would the $600 one be the right one? If I had bought the $80 one, would this GB70 be the right one according to tech support even though we already established it doesn't work?