Kiddies Account was never closed and now I'm being held liable for R700, the account was meant to be closed in 2013 already

Recently went into Standard Bank to upgrade my account from a Student Account to their Achieva account. The consultant that helped me then said I must pay R700 on a kiddies account that's still active under my name, when questioned about the account I was told it's in arrears and that it's pending closure since 2013. I recall closing this account and the consultant at the time saying I don't need to close just upgrade to a student account because of cash I was receiving, he confirmed the kiddies account has been deactivated and that it's inactive. No details changed and I've been receiving a set amount of money monthly. My question is why should I pay the R700 and why is this account not closed and still pending since 2013? Why is Standard Bank charging their clients for their mistakes? The branch I went to advised that they can try and assist to close the account but it may be an issue and I might need to go back to Centurion to close this account because they might not be willing to cover the cost, I stay in Johannesburg so it's ridiculous that I have to go back to Centurion to close this account when the instruction was given years ago. This is not my problem I expect Standard Bank to act on this and close this kiddies account, I cannot be held liable for money when the fault doesn't lie with me. This account was meant to be closed in 2013 and the consultant had to make sure it was done properly before I left the bank. Please can Standard Bank close this account effective immediately without charging me because I refuse to pay, this was meant to be done in 2013 already and I' m confused because I didn't open a brand new account the account was upgraded from Kiddies to Student so how on earth are there separate accounts that I'm now being billed for 12 years later? This is unfair. Please fix this.