Admin fee worth R1550

My grandmother opened an investment account from old mutual on the 28th of January, and the agreement was that they will debit R500 monthly from her account to the investment and it will earn interest especially if it finish atleast a year. 12 Months later she asked for the money back since it was not earning any interest whatsoever, but to our surprised they took quarter of her investment money saying it is for admin fees. How is that even possible? No interest was earned, now they are taking part of her investment hiding behind admin fees, an admin fee that is worth R1550? Please stay away from old mutual. there is no interest, the service is bad and the consultants are very rude.