FNB changing details on my account without my authorisation

FNB took it upon themselves to change the contact details on my account to my husbands contact details. I never received any communication about it being changed, i never authorised it. And now that i'm trying to find out what *** FNB did and who gave them authorisation to do it and get my information on my account correct that i supp**** to FNB when i opened my account. I have to struggle for over 3 hours with the useless chat service and bankers and have to accept some bull**** terms and conditions when FNB did what the hell ever they wanted on my account.