Unfair hasty decision Fnb

I was contacted on Thursday or Friday to make payment on my credit card as I was on arrears. I told the consultant I would on Sunday she further advised tht as long as my payment reflects . But surely it would and the Sunday is not treated as a working day so the arrangement would fall on Monday. As I was about to pay the 6200 as per arrangement the facility was revoked on my app @ couldn’t make payment. I contacted Fnb they told me my account has been moved to legal . The consultant was also astonished tht they would do tht on a Sunday @ I couldn’t call the legal team as they open the Monday. Monday I’m sent an SMS tht I promised to pay the amount of 6200 whereas Fnb has already revoked the facility. On Tuesday I’m sent a text tht I failed to make payment whereas I didn’t for Monday as promised with a reference number which highlights tht my arrangement was recorded.. I’ve never been so dissatisfied with Fnb worst bank ever