As salaamu alaikum, sister --
If you have a balance on your credit cards now, you can strive to pay it off as soon as possible and not use the card any more until the balance is paid off.
I thought about saying that, but didn't because Credit cards are not a necessity, when you can do pretty much the same thing using a debit card.
I find companies prefer me to pay with a debit card instead of a credit card. Some even have lower fees for purchases using debit instead of credit because they themselves are charged less for the transaction.
So I could have said, use a credit card, borrow the money from the card company but pay it back before they start charging you interest. But instead I said, use a debit card like pretty much most of us. pay for stuff with what money you have in your bank, so their is no risk of you being charged interest.
Pearl reread what she wrote again, and you will find your answer there.
Many people in the building trade work like that. It is possible to do it in a Hallal way. But that would require him making serious changes to the way he does business. I agree with you, that I am not sure he would agree to that.
The way he does business now is, taking the money from a sale after payment of debt and seeing it as the profit you live on.
While the Hallal way would be only buying with what he has, and setting money, and even then not all he has because he would have to keep some aside for doing the place up.
Or working with partners and sharing the profit the profit with them.
The harram way seems more profitable when times are good, but it also has greater risks. Because if he doesn't manage to sell at a greater price he is stuck with a debt that accumulates interest.
He knows more about his business then you. So I can understand why he wouldn't listen to you when you advice him on things you know nothing about. It would be better and more affective if you just tried to get him to fear Allah in general, on all issues.