Can no longer buy smaller data bundles

Since November 2025 my dad can no longer buy the smaller data bundles. It only shows the 3 massive bundles under the 30 day bundles. Using *135* doesn't show it, the vodapay app doesn't show it and Tobi just states there are no bundles available to buy. We are 3 people that are on prepaid, all on the same package/price plan, the 79c. Two of us can buy the small bundles but my dad's doesn't give the option. Very frustrating. Please fix this.