Debit my account for an amount i dont know

Its been 5 months now. Something named CHUBB NUDEBT is taking an amount of R234.77 from my account every month. I wrote to Chubb many times telling them to stop this, no response came . Every month I reverse this debit but they deduct again at the end of the month, and they deduct again the following month on the 15th. This has been going on since April. I am now advised to take them to the ombuds.