Cst

I am having some query regarding c form. I know basic about CST but I don't have in depth knowledge. If A of Mumbai sells goods to B of Jaipur then it is considered as inter state sales and CST will be charged @ 2%. A has raised invoice in favour of B and charged 2% CST in invoices. But the main thing I want to know that if A fails to collect C form from B later on then what will be the impact . I have heard many times that CST refund will not process. But I don't know how CST refund occurs .