It might help to read a little about how SEPA Direct Debit works. To begin, it's a European scheme, not American. Not every merchant can sign up for SEPA Direct Debit. They need another bank to be their guarantor (called your SEPA Direct Debit Creditor). When I have issues with a transaction and order a refund within 8 weeks of the transaction, I get my money back, no questions asked. I've used this to recover money from all sorts of businesses and government agencies.
The business can only dispute if I requested for my money back _after_ the 8 weeks. That's when the evidence and back-and-forth with the business comes in.