Bundles that expire in February 2023 are being used for current usage instead of bundles that expire at the end of the month

I bought a top up data bundle that’s expiring on 28/12/2022 instead of my current usage coming from this bundle my monthly allocation for January 2023 is being used up. When I enquired about this fault the call centre lady put me on hold for over 30 minutes and eventually I hung up without being assisted