Submitting wrong last time Reading

Submitted my first time Reading for electricity metre and it is wrong so my old supplier has send me a big bill as I contacted them regarding the bill they have asked me take get back to contact them with the correct reading how do I go about this

@mohammad3398 can you please email us a picture of your meter at help@bulb.co.uk? We’ll then agree a new change-of-supply read with your previous supplier.