Nedstar debt through Nu debt

These people debited my account numerous times without me even having approved their debit, on behalf of Nedstar, guess what my account at Nedstar is still not paid, and they now stopped sending me smss and Nedstar has started sending me threatening smss, when I call Nedstar they did not receive my money, and when I called Nu debt they said they sent the money to Nedstar last month already, I don’t even know who is lying