Thank you all for the quick replies!!
I did see the mother with the pups when they were 2 weeks olds.
She let us near her pups and seemed friendly, she let us all stroke her and then she fed the pups.
She did seem a little thin but I just put that down to just giving birth etc.
If i walk away from this do you know if I would be entitled to my £100 deposit back??
Im really upset this has happened as we were so looking forward to getting our puppy in a few wekks time.