FNB locking down my credit card at the beginning of the month, despite good standing. Can't unlock.

You've locked my credit card at a very bad time, even though it was in good standing. Now I'm sitting with bouncing monthly payments through no fault of my own, and I call in and the system is down for maintenance?! You're happy to take my money but not give it back when you're in error.

What's worse, my available balance is at zero, where previously it was at ~R5000. Have I lost money? I'm so confused after the explanations I've gotten, I don't know if that money is forfeit or I've payed some kind of fee, or if your system has just glitched and now I've lost thousands. As a person on the street, I don't understand your explanations, so you could me taking my money and I wouldn't know better. I'm honestly closing my credit card with you guys as soon as I can, I can't have you making my payments bounce every month!