Paying back the amount borrowed on the credit card

We had lived in Oman for about 3 years and during our stay we took a credit card and used it at times of emergency rather seeking help from our fraternity as everyone cannot help financially especially abroad. Therefore we took it and returned the amount within 52 days which prevented any interest. However we moved to China and due to meagre amount of cash we took the credit card with us as a backup because we were going to Pakistan and then to China. The process took longer than expected. We had used the card at the airport and did some other transactions however my mother kept 400 OMR separate from the rest amount. As mentioned earlier the process took very long so although we had the money and were fully prepared to keep it separate but we could not really return in within 52 days as my father was in China and was settling down there and in Pakistan without a male the survival becomes quite daunting due to some family issues. So now here we are with the card in China and have the money and have exceeded the time limit. I inquired before and was told by you that if we pay only the principle amount and not the interest we would not be punished by Allah. So now we want to send the money back. I emailed them but got no reply. I did whatever I could to get in contact with them but could not. So my dad was telling my mother to keep the money because every bank has insurance and after the time limit exceeds they put the name of the customer in another category where they only want to recover the main amount not the interest. So he suggested that start a business with the amount of money. She has approximately 1 hundred thousand rupees which is 1 lakh and then repay the amount to the bank, the major amount not the interest from the profit she will get. My dad is a business teacher and knows all about businesses. The following are my questions:

1) Is it permissible for her to start a business with the money she has and then return the money from the profit she will get?

2) We could not repay the money within 52 days but we intend to and have the money till now and have not used it and only will pay the major amount not the interest, so will we be punished by Allah?