Old PAYG $3 per Day Plan - Expiration

I have an very old, ‘grand-fathered’ $3/per day PAYG plan. I used to add $10 every 90 days to maintain the account. I used to be able to call in to check on “dollars and minutes remaining” to verify the expiration date. Now it seems like expiration is tied to most recent usage +90 days. Can anyone detail their understanding on the current mechanisms to maintain and check on balance/expiry?