Were they open between Christmas and New Year? There's a message on their website saying they're shut until 4th January, so they may not have seen your order yet. Even if they were trading, Monday and Tuesday were both bank holidays, so Royal Mail had a big back log waiting for them on Wednesday morning which will get even bigger because Monday (and Tuesday in Scotland) next week are bank holiday(s) too.
I assumed the email system
Would be working but I could be wrong. Bit gutted as I was hoping it would have been sent before Xmas. Hey ho, I will keep waiting thanks
I think a lot of online businesses (mine included) stopped processing orders after the last mail pick-up on Friday 23rd, as Royal Mail doesn't operate a 'first in, first out' policy with their sacks, so stuff dropped off on the Saturday would have been right at the bottom of the pile for going out when they started again on the Wednesday.