CariadAgain
NotSpaghetti
I am with M0nica here - do a couple really matter?
Unless they arrive "specimen items" if they are happy to cover the cost of replacement I think it's not s big thing.
I have left, been left, taken and allowed to be taken.
Unless you are already annoyed about something else it seems reasonable to talk about it.
Also, not everyone realises about plants being fixtures - and it's not as though you've completed yet!
You say their mum died so they may only just now be looking at the garden as it blooms.
They have asked you by email so haven't just dug them up.
I'd try to be accommodating.
It's always been my own experience with vendors, neighbours, buyers that they ALWAYS know what's what - but they just want to pretend they don't and hope you don't either and they can get away with try-ons. In any accommodation I've ever had - there was never one single thing worth having (other than my freestanding 1950s kitchen cabinet that the vendors stole from my starter house).
They just want to see what they can get away with ...
We'd put an offer in here, years ago, for a house in a fil,age. Everything was proceeding but the vendors kept putting obstacles in the way and delaying matters. Silly things like deciding they needed to take the garden shed and other fixtures.
We found another house, a new-build and because we wanted to proceed quickly with children starting at new schools, we bought the new house instead.