Tax Relax ******* ******ion Tactics

I terminated Tax Relax services last year, however they keep sending me threatening letters demanding<br> some imaginary outstanding fees. I owe them nothing yet they threaten to *******ly debit my account.<br> How can I stop them, please advise.<br> I am going to ask police to look into this matter. Tax Relax is financial ********* company and must be stopped.