My friend purchased an item with her membership card for me (with a discount). It should have cost £30 but with her discount only cost her £20.
She is insisting I pay her £30 as I'm a non member and not entitled to the discount 
She offered to buy it for me as she had a discount in the first place!!
AIBU to not pay £30? She's currently not speaking to me as I said I felt I should only have to pay £20.
AIBU?! 