FNB "stole" my SASSA R350 SRD grant and don't want to take responsibility!

SASSA paid me R350 grant for covid 19 relief of social distress,however fnb helped itself with the funds and only transferred R145 into an Ewallet account,now when I enquired with fnb they send into a wild goose chase-the branch sends me to the Ewallet department,the Ewallet department sends me back to the branch but nobody can explain what happened with the outstanding R205! I really need the funds in order to support my children as I have recently lost my ability to generate an income due to lockdown regulations