Lost of confidence and disappointed in African Bank - investment

I had an investment account which I had opened and had friends who were depositing money on this account and one of them made an error for 12 months of making EFT deposits with a different bank into the same account (however universal account, starting with 75) without using a correct reference i.e. starting with 900 but their own name. We only realised this error in November and went to inform African Bank so that they could allocate the money back into my investment account. To date I still have not been assisted by African Bank to a point where I have been the one who has been making contact with them trying to follow up on when they will be concluding the investigations etc. I have numerously also sent proof of payments for the 12 months in the form of a statement as per what my friend's bank provided to us but again I have been sent from pillar to post. My money is still not paid by African Bank. I don't understand how the bank cannot trace money that is deposited in their own universal account and allocating it correctly after so many months and numerous attempts to have them help with this query. They have provided with various reference numbers when I logged the query with them each time I contact them.