Settled loan account still deducting

I settled my loan on 11/04/2015 send through proof of payment, but the deducted again end of April. Upon enquiring I was told that they did not get the money. We realized that the wrong reference number was used, and send through the proof of payment again on 6/05/2015. Upon enquiring from my side again, I was told that they are still investigating and that the debit order will once again be debited end of May. Does it really take more than a month to balance payments? I send proof of payment again this morning and was told once again that they cannot assist me....???? Paid almost R70 000 which now is in their account and they still collect premiums from me.