Shocking treatment, overcharge

This company is the worst. I never signed a contract with them, they purchased Combat force and all they did is to send invoices. I cancelled my account and received a written confirmation that the account has been cancelled effective date 31st March. Then an invoice for the month of April, I forward the email saying that they should not charge as the account was cancelled. No reply. I called, and after having to wait 12 minutes in line I got the accounts in the phone, I was told that the debit order will go through but they will refund me, no date for that, no apology, just a very rude person in the phone. Absurd!!!!