Incorrect Gas Reading

I moved into the property on the 16th May 2018, the reading on this date was 6918 m^3.
I switched to bulb on the 8th June and on this date the estimated reading was 6934.
I have read the meter yesterday (30th Jun) and the reading is 6921 m^3.

The estimated reading is therefore incorrect on switchover. How do I rectify this, will this also mean my final bill from the previous supplier is going to be incorrect? Rgds

@ElliottM when meter readings are incorrect we can dispute them, however, there is a threshold and if your reading is close enough to the estimate we would be unable to dispute due to the change request being automatically rejected. Due to the reading being only 16 units different we would be unable to change this. If you have any further questions give us a call on 0300 303 0635 or email at Best, Chad