Wrong Size in Basket

[GreenManFest]

Customer is adding an item to their basket and it's showing up as a different size to the one they picked - any thoughts?

[GreenManFest]

It now seems certain items are doing it and being added to basket and purchased - please help we're getting lots of orders through

[Laza_Binaery]

@GreenManFest 

It would be beneficial to all who take a look on this topic, to tell us your store URL. 

Without it is a guessing.