cant or wont cancel monthly contract

I got an idmobile sim on a monthly contract on 22/10/2015, I decided I didnt need it and phoned to cancel my contract on 3/11/2015. Customer services told me there would be no charge because I cancelled within 14 days. This is also stated on their website t/cs<br> I cancelled my direct debit. I got a worrying email on 5/11/2015 warning me that there would be charges for cancelling my DD. I phoned and emailed again to clarify. I got an apology for incovenience and was told my contract would be cancelled forthwith. <br> I reccieved a threatening letter on 22/01/2016 advising me I owed them ?30.20 and a further ?8.50 for January and if I didnt pay the debt would be transferred to a debt collection agency for which I would be liable for charges.<br> Also I would be referred to national credit reference agencies.<br> There seems to be no way I can contact anyone at idmobile who can cancel my contract or if I have been ill advised by customer services revise my bill from the cancellation date.