Disgusting and Dishonest

My account had been debited by more than double on the 25th April 2023. I have been liaising with multiple agents on my refund and have received a different story each time. Today I was told my refund was rejected but no further explanation was provided, neither was an explanation provided on why on earth more than double was debited WITHOUT MY PERMISSION in the first place, which actually boils down to theft since I did not authorise this debit. I have been a customer for almost 20 years and have never missed a payment ever. This is absolutely disgusting service provided to a loyal customer. I WANT MY REFUND TODAY!!!!!!!!!!!!!!!!!