Unauthorized deduction on Cheque account

Unhappy about service received at Hatfield branch Pretoria. My dad (HL WEDOE ACC NR ***) has an unauthorized deduction on his account R1633,80 on the 22/04/2021 (ibank payment SA Homeloan). My dad’s home loan was closed many years ago!?? He is a pensioner and this is a huge amount just suddenly deducted with no warning or explanation! When we phone the branch we are told he has to come in to sort it out?? My dad has COPD, and we try hard to minimize his outings. I was wondering if there is another way we can sort this matter out. I am willing to come on his behalf as I have signing authority on his account. I was hoping someone would understand, this is after all not his fault.