Disconnected mobile service, but direct debit charged

[helemetzoo]

I was on a pay monthly sim-only card and I gave my 30-day notice period last month and recieved a letter stating that it will be disconnected on the 9/06/2018. However I just found out that I was charged via direct debit on the 19th.
Obviously this shouldn't have happened and I need to get my money back. Who would I need to call?

[BandOfBrothers]

When a person gives 30 days notice then Vodafone collect the final bill in approx 2-4 weeks which is followed by a sorry your leaving letter and a £0 bill which confirms account cancellation. 

If you believe things are wrong then phone customer services or use live chat to ask them to clarify. 

More info in When-will-I-receive-my-final-bill.