I would like the forums opinion on whether I should have won the jackpot. -snip-
Of course did you win the Jackpot!
Your original bet was a max bet. Then you won 4 max bets with the 3 airplanes on 2 paylines and each of the 4 free spins are technically a max bet.
The slot do not run without a bet and whether you paid directly or won the 4 max bets does not play any role for to be eligible for the Jackpot.

-> "Jackpot cannot be multiplied"
confirms that Jackpots are eligible during free spins. They can not be multiplied, but they are clearly eligible!
Betcoin.ag is of course saying that BetSoft is to blame. Who can I dispute this with?
Did you sign a contract with Betsoft? If not, then betcoin.ag would be your contract partner.
If you buy a car, the seller is your contract partner and not the producer or software provider!
I said betcoin.ag
would be your contract partner, because there is no juridical valid contract between you and the domain betcoin.ag or however they call it. So from a juridical point of view, you can consider everything you get from Betcoin as a gift.
If you would know who the operator of Betcoin is, then you could sue them in the applicable jurisdiction...

This guy is manipulating the truth again. The image above is not associated with the game in question....He is lying! The game in question was called "The Glam Life" and if you look closely, you'll find that there is no "Elfania" symbol in the "The Glam Life."