What on earth actually is document duty? Your legal feels look pretty similar to the UK, but no idea what this document duty is. Is that some sort of tax the Guernsey government have? Do you have a form of stamp duty? - or is this probably it?
I was thinking that. Conveyancing fees down here are maybe £2k.
Pretty sure document duty is their form of Stamp Tax. Stamp Taxes were literally the price you paid to get the documents officially stamped in ye olden times.