Even DarkStar_ said this himself and wrote that "there's a reason sportsbooks don't cancel all bets that have had line movement against them."
That was a generalized statement about cancelling bets. My current stance based on the information I have is that FJ are justified in cancelling your bet. Quote this

And this is a general/regular situation and is no different from any other swings of odds that happens every day in all sports either, so what you said is true and applies to this case as well.
Kinda funny that you're trying to take it back now lol
Anyways, I'm not going to be saying anything more about this case unless someone has a question about what happened and needs clarification on something.
I've said this to you before: 2.6 instantly dropping to 1.3 is not normal line movement. Had it slowly dropped from 2.6 to 1.3, I would definitely side with you. One shows a likely odds error, the other shows natural line movement.
I stand behind my statement for natural line movement. I disagree that sportsbooks should be forced to pay odds errors, as this would likely end up hurting legitimate players through increased vig across the board.
Here is the full context behind my post:
FJ as a sportsbook has every right to cancel any match for any reason so long as they do it before it starts. You are not entitled to something because of it - had they done it when the game started or afterwards then you'd have a case here but as of now there is nothing. Bet was canceled BEFORE it was being played, what happened after matters not.
They might have the right to do it, but that doesn't make them not shady if they unjustifiably cancelled a bet. There's a reason sportsbooks don't cancel all bets that have had line movement against them.
I was disagreeing with Hhampuz's statement that they have every right to cancel any match for any reason.
According to their own reasoning, they canceled my bet because odds dropped from 2.6 to
1.7 - this was literally their official statement and reasoning (no mention of a technical error at all either). That is 100% not that uncommon and I've seen it happen countless of times.
But even if let's say they did drop below 1.7 or they used a lower number in their email, I've still seen this happen many times from around the 2.5 mark, yet bets never got canceled because of it. And specifically for this match, other major betting sites did not cancel this bet for their users when he dropped to 1.7 or lower from 2.6+.
Not to mention have been much more
extreme cases where odds dropped from 5.0+ to less than 1.5 (due to a clear technical error), and yet reputable bookies with the right ethics still awarded people who bet on 5.0 their full win despite that kind of massive swing, much like LEVSKI7 shared on here many times. (Although they could have easily said no and had a much stronger reasoning for not doing so)
Anyway, I've done enough arguing about this case - everything that I had to say I already said previously, or was said by fellow community members.
You can read a summary of all what everyone had to say about this on page 463 if you want a TLDR and not read everything.