Fake ratings and reviews on IMDb

Hello friends
Our indie film was recently released on a few VOD platforms in the UK and is soon coming to North America. After a good festival run we got some great reviews and were looking forward to the premiere. 
Our IMDb score was very high (above 9, which of course is unrealistic, but not unexpected as it was just the people very close to the project and the festival audiences who had seen the film and rated it) and then the night before the release about 15 IMDb users ganged up on it with 1s and 2s and brought it down to 4 something.
I asked IMDb about this and they explained a few things:
"Although we accept and consider all votes received by users, not all votes have the same impact (or ‘weight’) on the final rating."
"When unusual voting activity is detected, an alternate weighting calculation may be applied in order to preserve the reliability of our system."
"To ensure that our rating mechanism remains effective, we do not disclose the exact method used to generate the rating."

Of course, what this doesn't explain is why 15 voters coordinating to give very low ratings within a few hours BEFORE the premiere isn't considered unusual and in fact is encouraged by IMDb who assign these 15 votes much more weight than the other 95 the film had until then (the arithmetic mean was above 8 but the weighted average was 4.6 - the latter is what actually appears on IMDb).

IMDb also explained that "That's quite common when the statistics are first compiled. It settles out after the voting gets north of 10,000 votes. So the rating comes up over time"
Of course, for small indie films the chances are that the votes will never reach 10,000, especially if their rating is sabotaged before they're even released.

So after failing to provide any logical explanation why these 15 votes are not considered unusual and in fact count more than all other votes put together, the IMDb spokesperson proceeded to explain that:
"the voters think the film stinks"
"Sabotage only happens because of the persons that the producer, director, or whomever, have pissed off, seek to extract their brand of justice"

I found a few things really bizarre in this story
- IMDb's weighted average formula
- IMDb's way to identify unusual activity
- IMDb's refusal to understand what I was actually questioning
but mostly the fact that their spokesperson's answer to all of this was to attack me, suggest the film stinks and I've pissed some people off, which is why I now deserve to get the film sabotaged.

I spoke to a couple of filmmaker friends and they had similar stories about multiple bad votes coming in within a few hours/days. I think it's a case of someone not wanting small indie films to come up on searches like "best rated on ..."

Has anyone here had such an experience? Did IMDb do anything about it (apart from blaming you for it)

Thank you,
From a producer who must have pissed someone off, according to IMDb