Drop the Social Team a message through social channels here : Contact Us@Rolly11 , they will be able to let you know the best method to pay the debt and also advise as far as your credit file is concerned.
You can have a word with customer services on Live Chat or call 0333 3040 191 and they'll arrange for you to pay as long as the debt is still with Vodafone UK and hasn't been passed to a debt collection agency @Rolly11
