I was under the impression I could get a new car on finance when mine comes to an end but was turned down for finance -do not feel this was made clear it would happen

Can I cancel my IVA if my circumstances have changed and go back to paying my creditors as I had before? And how do I do this? Will my credit score go back up if this is the case and will the money I have paid in to the IVA be taken of the amount I owe?