Planet Fitness tried to debit an un authorized debit ( ******* )

I had an agreement for the last payment I ow Planet Fitness. due to me not receiving my salary for the past few months, I told them I'll come and pay in the gym once i get money. now they tried to deduct a portion of what i ow, causing the debit order to bounce and costed me R147 for a unsuccessful debit at the bank. as if it is not enough that i do not have money they just make the whole situation worse