FNB changed my son's account without my knowledge or approval.

My son turned 18 in April, he is still in school and under my roof. Now FNB took his account away from my profile and changed his account from an FNBy account to an adult account. How must he pay bank fees, all this without FNB contacting him or me. He also has an Investec account but I will have that on my profile untill he is 21 or become independant. I phoned FNB and nobody can tell me how much his banking fees now are. My son gets all his money from me as pocket money so why has it been taken away from my profile?