FNB say I owe them 11k for doing nothing

I had a normal account with FNB and I was getting my salary into it, but later I changed to Capitec but did not close the account. I know there were supposed to be some charges as debit orders bounced but come on FNB charges to the R11000, that ridiculous, FNB have since handed over my account to the lawyers for the amount of R11000 and these lawyers are nagging but cant tell me why I owe FNB so much as, my problem is I did take a loan with FNB, I did not have an overdraft, I have been asking these lawyers to go back to FNB and tell them my concern but they keepon nagging without solving my query.

FNB let me know how you account abandoned account accumulate R11000 in charges, how this 11K came into being,

Dont you put on hold account after three months of being used? how the 11k accummulated.

Ill be paying 11K for what?? Charges when I never used your money, this does not make any sense and does not make any logic to me 11K for doing nothing hhaibo, I have family to look after, I cant pay 11k for abandoning the account this is ridicuous really ridiculous