If the value of the parcel is £15 or less there will be no VAT charged
I could be wrong, but as far as I know the "low value exemption for VAT" was abandoned some while ago. Small companies here used to send small boxes of flowers over to the UK without VAT, but that has all been stopped.
Its a mystery to me why the £23 charge is there, it sounds more like a customs duty rather than VAT or perhaps a combination of those. Or perhaps its just a mistake???? Sometimes I order guitar stuff from the USA, almost always I don't pay customs, but the carrier always wants an amount for VAT. As we (Channel Islands) are not part of the EU and don't pay VAT, I always have to get in touch and explain this over and over again.
I would want to find out what the charge is for, before paying up.
"When I was younger, I could remember almost everything, whether it happened or not." Mark Twain