Debit order requests without utilizing them

Broll recently took over the company where I rent a storage unit. They received my debit order 15th of May, and according to emails in June it was loaded, but not deducted from my account. I had to follow up - my first enquiry 9th of June went unanswered. Later I enquired again after receiving a promise of 5%discount this month if I send in a debit order. I was then charged interest though in my mind it was their error not mind, and I paid the original amount via eft. It is now the 3rd of July and the debit order has once again not been acted upon.... It seems like an incredible waste of time and money to me to keep following up on what's supposed to happen automatically from their side. If they want me to pay via EFT .... just say so. Don't beg me for a debit order if it's only purpose is so you can charge me interest and waste my time.