My late husband had a cheque account with FNB, I'm battling to wind up his estate because his bank account was emptied and FNB cannot provide proof of how the money left his account as it was closed as soon as he passed on 4 years ago

My late husband had a cheque account with FNB, I'm battling to wind up his estate because his bank account was emptied and FNB cannot provide proof of how the money left his account as it was closed as soon as he passed on 4 years ago. My attorney is being sent from pillar to post by the fiduciary department. We've laid complaints and made numerous phone calls but there's no solution from FNB.