61 days LTE data expired in 30 days

I bought 1 terabyte LTE data on the 20/02/2025, which was supposed to be valid for 61 days. On the 20/03/2025 I had no network connection and when I checked my data balance, it showed that I had no data remaining. I had to buy more data on the 20/03/2025. As far as I am concerned, the data bought on the 20/02/2025 was supposed to be valid until around the 20/04/2025. Can someone please explain to me why my data disappeared before the expiry date.