In the first place TS, have you checked whether this credit card debt is still active?
Since you said you found some old bills/statements while cleaning up. Maybe your father paid it off after he withdrew his EPF?

Cos 15 years is a long time for the bank to still be keeping the debt. Usually it's written off after 7 years.
And why hasn't Debt Collector come to house to chase your father to pay when he was alive?

I know cos many years ago when I was retrenched, I
couldnt pay my credit card debts. It was during economic
downturn.
When I finally got a new job, I paid back a little. Then, when I could afford to pay back lump sum, the bank told me the account no longer available( means they had written it off.)

So, better check the credit card number if still active 1st