@Clair I don’t understand why you were told, you had terminated your lease early, as you were already in a lease extension! Whils’t a total of £700 (350+250+100) GCB was correct, as you didn’t quite reach a full 5yr lease, I’m confused why you were told this.
@BigDave would you mind having a quick read over this topic, incase I’m missing something 🙂