Where has all my Data gone. Is it a policy of Vodacom to confiscate non expired data?

Data loss, Vodacom do not respond to emails on customer care. On 26 may 2023 I bought 1 gig of data for my router. This I closely monitored and to avoid data loss due to OOB, I selected Flight mode when not in use. On 30 may I still had 750 meg of data left, non of which was used. Then on 1 June, it was all gone. This data should have expired on 26 June. All my requests sent via customer care have been ignored.