RUDE AND *********** TELLER

I've been a client of Standard bank for the the past 3 months and never did I receive such horrible and disgusting service from Standard Bank. We went there to collect cash sent by Moneygram from another country. We were told that we need an ID and proof of residence, which we were adviced that we can get via the app as I am a client of Standard Bank. When we got to the teller who was supposed to assist us, she rudely ******* the information we were given by the receptionists and said they do not take bank statements from Standard Bank and we need one from a different bank(how true is this). We then went back in disappointment and came back the next day with bank statement from Capitec.She still dismissed us rudely and said she needs 3 months bank statement which is not even stipulated anywhere on the bank's Moneygram policy which only stipulates that a proof of residence less than 3 months old is needed. Not only does she not understand her work, she is rude in response to the clients! I wouldn't lie, the rest of the staff was friendly and helpful, the receptionist even offered to take our numbers and called to come back when the system was online. How do I lay a formal complaint against this rude teller who even up to this point, refused us to get our money? Can I please get the process of how to lay a formal complaint.Her name is Refilwe and she works at Lilian Ngoyi Standard Bank in Tramshed Pretoria.