Atrocious service

My Bradlows debit order went off my bank account on 31st May. Since then I've been harassed by Bradlows accounts department for 6 days, up until 4 minutes ago. I'm on the verge of losing my job over this. Just received an email from their collections department. I have a photo of my payment reflecting on their system on 31st May. I spoke to 2 ladies who both assured me it IS paid, NO arrears. And they promised to sort this out. I've had so many calls and messages, and mails at work regarding this, and still on a Saturday they carry on. Just yesterday they promised me... No more calls and messages. I've received 2 msgs, 1 call and 1 mail this morning. What ELSE do I need to do from my side??