Vodafone

My phone and airtime contract ended 31/01/19. I don’t want to continue vodafone contract as I have another number. They insisted I keep the number or give to someone else. Told them I don’t have anyone and want to not continuing. I’m paying £48.16 for phone and airtime. Now the contract ended I am not supposed to pay anymore the phone and airtime. But because I was late for 2 days as they kept transferring me to other department for other stuff, they are charging me same as if I am having contract of phone and airtime. I am giving them one month notice. They said I will be charged the same amount £48.16 and I don’t understand why? I am not having new phone contact and I am ending the contract which already ended 31/01/19. I understand if they want to charge me the airtime as it is still on till 3-03/19. But why charging me the phone when it’s already paid in full?