Oushk pharmacy, no delivery

I was due my delivery from Oushk on Saturday. I was home all day, got a notification to say my parcel had been delivered. Checked around my garden etc but no delivery. Looked at the picture to see someone had collected it from a house which looked like my neighbours - but all our houses are identical so could be wrong.

Checked with neighbours twice, those who answered had no delivery for me. I contacted Oushk on Sunday and they called me today and said they’re opening a claim with Royal Mail and could offer me £50 off another pen. I explained my circumstances but they have said that it’s out of their hands. Where do I stand with this? Pens aren’t cheap so I can’t afford to just buy another one whilst I wait potentially weeks for them to discover what happened with my pen. And even if a neighbour had brought me my pen round at any point now it definitely wouldn’t be warm?

I am so disappointed as I know I can go a little longer without the pen but at the price point I don’t feel like I should have to?