If it was shipped from the UK to a UK address it should have arrived after 2 days going 1st class. Could be a little longer at this time of the year because of extra Christmas mail.
Perhaps the correct postage was not paid or the correct address used both of which can
be a problem with using ebay
It should be there today,but it depends where in the nation it was posted and where it is to be delivered
If you don`t receive it contact the seller who will have to take it up with the courier.
Where was it shipped from?