Debit order on wrong day!

Telkom did a debit on our accounts on the 25 th of February instead of our agreed debit date of the 1st of each month. Now those debit orders bounced . I was charged R80 by my bank and guess what Telkom also charged me R200. For a returned debit order which was their fault. I never gave a mandate for that date . Please assist me to get a refund from Telkom. I can assure you I was not the only client who was done dirty by Telkom