Capitec allows unauthorized debit orders and ***** and refuses to assist me

so a unauthorized party has been debiting me for months forcing me to reverse the debit orders monthly encoring penalties, capitec says the party involves changes the reference every month so they cannot do anything, the party debiting me is unorganized chaotic and have no contract they can produce proving i agreed to the debit order mandate, they use to debit me once a month taking R299 now they debit 3 times a month R299, R299 and R99 ( 3 reversal fees to be paid at R120)

i am very concerned that they are able to debit me without my consent and keeping me liable for the cost, i cannot change my bank account as all my business is linked to the account and changing it would be a extra cost and a administration nightmare