Terrible service - Reversal of Transfer

I accidentally transferred money from my cheque account, on my FNB online baking, to my vehicle installment account instead of my savings account. I have called twice to have the funds reversed/refunded and was told the second time that it would be escalated. It has now been more than 3 weeks since my first call and 6 days since my last.

This is my money, that I require for January but they have kept it regardless of my attempts to get it back