The rigging would have to be fucking astronomical given the polling.

And there is a double barrier. The October referendum is just asking IF a REAL referendum should be had. A vote about having a vote. Even a "yes, have a vote" result would be an incredible deviation from polling. Not just a little. A LOT. A full supermajority polls at "no". Even if the next largest block of "i don't know" swung entirely to "leave" it still shouldn't be close.

So before any real vote could even occur, the tampering would be plainly apparent.