Bad service from nedbank ( foul play)

I received bad service from nedbank menlyn maine, I made a payment on the 14th of September into my account which reflected that the money is there, but I was called and told my account is overdrawn but I had put money via eft from capitec account and they said the money bounced back into my account but 2 weeks went by I saw nothing. Last week they sent me an email to say that they've sent the money back into my account the transaction was successful but still I haven't received my money and now this morning I called they telling me they can't find the money. How is it possible! Money can't just disappear and why did they lie to me because I even sent them my statement as proof that I haven't received my money but still they are failing to bring back my money