Direct debit

I have request to have a once off payment to be taken from my account as the account was behind due to direct debit not going thru on time. I request from the agent and she then says she will arrange it for the 27th November 2015 I then receive an sms saying my debit Oder will be taken 28th and again they still have not taken the funds as promised and I then call again. The agent says ok they can request for it to go thru the same day as its before 10am, to day is the 30th and still nothing has been taken the agent says she can see the funds it's gone thru but nothing has been taken from my banking account and this after they wanting to threaten me with legal action.