Horrible service

I am so disappointed in the service of this company. When i made the application with the sales person Werner, he was so nice, application was completed. I have a linked account on my capitec. He used the linked account for the debit order, which i rectified immediately &he told me np it will be changed. Monthend comes they use the linked account, after i had changed on application. Now i am charged R75 failed debit order. I want that reversed or i am going to throw a tantrum. I then did an eft but every single day i received a what app that i am still owing. After i called them, they said they rectified it & the next couple of days i was receiving a whats app every morning telling me to pay my account of R0, so how much is that, my account was not in arrears. Now i receive this message from the sales person Mam "unfortunately i cannot change details whereby it was verified." after he told me on the 3.7.25 that the banking details will be rectified. I am disgusted & disappointed in the bad quality of work these people do