Reliance Mart — Bought 3.2kg of sugar but they billed for 6.4kg

Bought 3.2kg of sugar and they billed for 6.4 kg, it came to know me when I reached my house and I came again to store it took 7.5 km to reach store from my house, after reaching store I told about the issue and they told me to wait and they will check cctv camera and am waiting for half an hour, it's the issue of biller on behalf of reliance smart, still now am waiting in store