Handed over to lawyers without communcation

My wife has an account with Woolworths that she paid off over a year ago. We stopped receiving statements and assumed that nothing was owed anymore. This week she got an sms stating that her account is arrears and that she needs to pay R90. She went in to a store the very next day to find out more but they weren't able to tell her why she owed that amount and also that she wasn't allowed to settle the account in store as it was handed over to the lawyers and that she needs to pay the lawyers a R1000. We never received any communication or statements other than that one sms from Woolworths and we would of sorted out the issue without the need to escalate if they had communicated to us