Help identify Delphinium disease
 

I have two Delphinium plants purchased about a month ago from a local garden centre which seem to be diseased.
They have been under attack from slugs but think I have controlled the slugs now with pellets and beer. Maybe too late.
I have kept them well watered, also put down some home composted mulch, which may not have been a good idea. I am a novice gardener and the compost may have been diseased.

Should either or both plants be uprooted?
Can I get a refund from the supplier if they are this badly diseased?

I wold like to post an image, can I do that in this forum?
Many thanks

I have attached appropriate images, is this the correct way to do it?