overcharge of interest on 12 month loan account

i have been overcharged interest on 12 month loan with Finchoice - i made a debit order payment on 18 March 2022 of R2 499.74, then an additional R24 980.41 deposit into account which is a total of R27 480.15, to my surprise FINCHIOICE charged me a settlement interest of R2 403,26 Which was supposed to be a refund back to me as their settlement letter quoted an amount of R22 070.60 - i called their call center and spoke to Thabisa who has been very rude to me and just put the call on hold for over an hour without speaking, as i type now i am still on hold with no help