Doubled billed in a month

I am very disappointed with ABSA vehicle division , I all of a sudden have an area that not their consultant can explain its from where.. the is a month I was double billed , I got a statement and was told same month I was bul**** on the 25 of the same month , so I getabill on the 10th of every month andthe is another one done behind not sent to me but created on the 25th ..sadly it's unexplained ..yet I am handed over due to me disputing since the finance department failed to give a straight answer as to why I'm double billed.