Broken sandbagging protection system

At the beginning I must to apologize you, as my post will be a bit salty. I want to speak abut a thing I encountered in the Arena. In the Tournament I played, I encountered sandbaggers, with lvl around 400-600 but playing like masters. One of them was even wining the tournament (he progressed around 300 rank points in this 2 hours), at least as long as I was tracking the event. Of course I dropped because of this situation and series of loses. What was my surprise when I was not able to join next Arena, because the system considered me as the sandbagger... Really, what a genius invented this broken system, which punishes victims instead of perpetrators?

What am I supposed to do now? I could play with some high ranked players to fast progress to my previous rank (now I'm around 150-200 below), but the system does no let me set the lower border higher than -25. I feel like in a trap, and the one thing is to slowly rebuild playing with low ranked players.

Those are two separate but related problems.  

The first-- the problem of low ranked players winning arenas-- all you can do is report them and hope they get banned from future events. That problem has been around as long as arenas have been around. After hundreds of complaints, chess.com tried to reduce it by restricting players from entering events when their rating had been much higher recently.

That's what caught you. Your own rating has fallen to less than 800 after initially setting higher than 1500 only two months ago. 

I am not sure what the threshold is but I would guess that you need to get your rating back above 1000.

Is it my fault that the system highered my rank after first 10 matches? I never had so high rank on any chess site ever. Slightly under 1000 is my typical rank currently, so no wonder I stabilized on this level (until I started Arena). And no, the threshold is not above 1000, I was blocked from Arena around 830 or something. So again - where is my fault? I play fair, do not use engine. I cannot be punished because I had some luck in first few games after creating account.

It's not your fault but it is an unusual situation and there are very few 800 rated players who can beat 1100-1400 rated players three games in a row.

I'm sure you understand why chess.com would put a system in place to try to address the problem.

Ok, but what am I supposed to do know? Delete account and create new, trying no to play to good in first few rank matches? I do not feel it is good solution. My history is not long here, but I would rather prefer to keep it. Any way to play with ~1000 players to fast rebuild my rank?

I'm sure that if your real rating should be around 900, just playing random opponents will raise it to that level again pretty quickly.

Not as quick as I would, playing with better players. It's better to rise by 12-14 points per game, than 5-8.

"What am I supposed to do now?"

Just play chess. There's no requirement to play in arenas. (I stopped trying due to the problem you mentioned - low-rated opponents playing top-notch chess.) But each day I have no trouble finding random opponents in the pool.

Yes, but statistically, your current rating of 780 is pretty accurate.

Statistical a horse and a ride have three legs each . And what does it prove?