Vodacom Debit order

i have contract with Vodacom on December I missed a payment which is 236 monthly so they added penalty because of that which I did not mind. On January towards month end I made a payment of 336 via Vodacom App and on the 29th they came and deduct R236 according to me I have settled my areas I even called vodacom during the month of February the lady I spoke to she said she can see the payment she will even send to accounts for them to update it now to my surprise month end they came and debit 336 which I don't even understand why they deducted that money because they were suppose to deduct 236 when I call them today the guy called the Thulani is telling me that I was not supposed to pay via Vodacom App