Unauthorised Credit Limit Reduction

FNB has decided ( In the Middle of a Pandemic ) to reduce my wife's credit card limit. They have not sent any notification, the funds that go into the credit card is more than the limit... meaning we not in arrears and we always transfering money into it to avoid fees and keep it in good standing. That is the only money we have left as I am not working due to the pandemic and we relay in the credit card to keep us above water. How do you reduce someone credit card without notification and in the middle of a global pandemic where people do not have food and are not working. Let alone being in good standing with the credit card and not missed a payment. My wife will be changing banks and so will I I'm sure this is a way to recoup funds and many people cannot afford their accounts....and FNB is giving payment holidays but taking money back from loyal clients