The worst internet provider ever!

I contacted Rain on the 1st of December and canceled my subscription. I got an email with a reference number for the cancellation. Now I receive a email to say they will debit be earlier this month due to the 1st of January being on a Sunday and a public holiday. I contacted them now to find out why I am being debited as I did cancel it on time, to which the sales lady advised me that it is not canceled and that she will now request for it to be canceled and that I will still be debited. How does this work?!? I canceled it on the 1st of December and now I need to pay for another month because they did not cancel it. Shocking.