Sorry, i think i managed to delete my original reply whilst trying to edit it, here it is again:
Well, the main reason I fell for it is because I had just done my first ever tax return this year myself, so I believed them when they said there was a few errors. They then passed me to someone from the Ministry of Justice, using their phone number (Which I checked when I received a call from them ‘02033343555’) They then told me, because of this unpaid tax, there was an arrest warrant for tax fraud against me and to remove it I needed to pay. I asked the person for some identification, and they told me there badge number and name which sounded legitimate, followed by them shouting at me not to waste time as I could be arrested at any minute. I was then told as soon as I pay and the arrest warrant is removed, the money pay would be refunded instantly. They then said the ministry of justice declined the removal of the first offence as there were 5 other arrest warrants which needed to be paid before I could clear my name and get my money back. So I paid
. They then said I needed to pay for the paperwork to be sent to the Ministry of Justice, the police and myself. This is when I thought something was up and I asked for them to give me back my money and I was promised if I paid for the paperwork I would receive all of it back. I did not receive any money back. 
The reason I still paid the money, even though there were warnings, was A: I was panicking and just wanted the arrest warrant to be removed and B: The scammer said that this was just an error with my bank and that it usually happens to people when paying HMRC. It also didn’t help that the same warning popped up only a few days ago when I paid a friend.