In February 2025 I returned their router and cables after I was advised by their customer care when I requested to terminate their month on month contract

In February 2025 I returned their router and cables after I was advised by their customer care when I requested to terminate their month on month contract.I called their support to confirm the cancellation,the consultant confirmed the cancellation but to my surprise they are still billing me for data that's not been used since Dec 2024 and they are threatening me with legal action