Unauthorised debit orders

I noticed that a debit order went out of my account in May 2019 and again in June 2019, to a company called ZFunerals. I phoned my bank and they led me to the contact details of ZFunerals. When I reached them to ask about why the debit order was made out of my account and who provided authorisation, they asked if I wanted it to be reversed with not many questions asked. After a couple of phone calls and at least a week the refund was made, the reference now being Zingzila. I phoned ZFuneral to confirm whether that refund was from them and they confirmed that it was. I then asked them to still let me know how access onto my bank account was granted. They said they're still busy with the investigation and they will let me know the findings within 48 hours, yet they've been busy with it for over 48 hours.

My gripe is that this company accessed my account without my authorisation and they're taking long to inform me of how they accessed my account.

I think the legality of ZFuneral should be investigated.