Why was my Account handed over??

Good day, I had an arrangement with SBSA to repay my Blue Bean credit card account. I have been doing so for the past 3 years and never defaulted once during this time. Every month I would get a phone CA from them to say thank you for the payment and they would ask when will I make the next payment and I'll than tell them the end of the following month. Now, on 15 Feb 2020 I get a sms from MBD to say that SBSA handed my account over!! And I'd like to know why, I went to Std Bank in brackenfell and the lady told me that they cannot see any reason or notes on my account.