It will produce more coalitions.
Objectively false. Studying past elections in the UK shows that it would have led to hung parliaments no more frequently.
It is used by only three other countries
Objectively false. Nine, actually, including the USA and the UK for some elected positions (such as in trade unions). The fact that it's under-represented in parliamentary elections is not an argument against it.
It allows the second or third placed candidate to win
Under AV, the person who won under the rules of AV wins. Under FPTP, the person who run under the rules of FPTP wins. Sometimes these two are not the same. There is nothing inherently more accurate about FPTP. In fact, according to things like the Condorcet criterion, FPTP is objectively worse.
It will cost the country £250 million
Objectively false. Of the quoted £247m, not a single penny is actually true. The referendum itself is £91m, a sunk cost. Voting machines might cost £130m, but AV can still be hand counted and machines might be used under FPTP eventually anyway. Explaining AV to voters will not cost £26m. You can explain what to do in a single sentence. Further information is available in many places on the web, for free.
Remember the core principle of British democracy: every person gets an equal vote.
Except FPTP guarantees that not everybody's vote is equal. It's actually possible to calculate how much an average vote is worth in a particular constituency based on the size of the standing majority- it's never 1. Under AV, the 'value' of your vote improves. There is nothing in AV - nothing - that changes One Person One Vote. AV is called 'Instant Run-Off' in the US, because that's what it is. It's a much more efficient way of having a series of elimination rounds to get a winning candidate. If your candidate is eliminated, it is counted differently in subsequent rounds. If not, your vote is counted for the same person in future. At no point is any person's vote tallied more than any other person's.
I'm used to lies in political material. It's par for the course. But usually it's something that's at least plausible, an opinion or a prediction. It's usually difficult if not impossible to objectively prove it's false. Every claim made by the No2AV campaign is objectively false, or deliberately misleading. If No2AV succeeds, this is what we can expect out of electioneering for the future, and it stinks.
Yes to AV, because the people behind the No campaign deserve to be publicly humiliated.