unauthorized debit orders

i had an arrangement to pay my fnb temp loan account with Groenewald Lubbe attorneys however i did default a few months but the payment was made the following month however no one contacted me when i defaulted so i assumed everything was fine cause payments was made the following month however the full amount was debited on the 25th of may 2019 and i didnt budget for that i went to fnb office holding on for more than a hour and no one answered i had to leave today finally after 1 hour i managed to get hold of fnb and i was advised to call groenewald lubbe but now i cant get hold of the compnay tried all the numbers when i got hold of them once i asked to be called back cause the line was bad and no one called me back and i urgently need my money back as the attorney also debited the installment for the account can some please contact me urgently!!!!???