Unauthorized debit order

Good day

I have a very bad experience with Cartrack, with regards to my debit order. I have signed a mandate with them to debit my account on the 20th of every month, suddenly on the 15th of December 2024 I receive messages saying that they have missed payments from my account, who told you to debit on the 15th? do you even know this is affecting my credit score negatively? I'm very disappointed =, I thought this is a legit company, but I was wrong