RCS where is R11 000 from my account?

I had a credit of R5156 on 03/08/21 while trying to access more funds, the RCS system responded with an error message that my transaction cannot be processes, few minutes later i receive a message alerting me of impending maintainance that will commence later in the evening. 2 days later, im supriced that i have a -R6000 on my credit without having conducted any other transaction since the error message. Now where did around R11 000 go to?