Discrepancy over first meter reading

When I changed supplier as of 1st July, Bulb queried the meter reading that I supplied for gas saying it was too high. It was in fact the reading I gave to my previous supplier for my final bill which which then cost me about £700 to close that account - which I paid. Bulb queried my initial gas reading and said it was too high based on their validation process. I submitted a photo of the reading and the smart meter serial number as requested. I heard nothing so assumed that my reading had been accepted. I’ve just submitted an updated reading as it’s been 3 months and it’s been queried because it’s too high. I noticed that the reading they have for my July submission is NOT the starting reading I provided but their ESTIMATED reading so it’s unsurprising that it’s flagged as too high again. I am worried sick that I will be charged for the difference between bulbs estimate for July and my actual for October and be billed for gas I have already paid for with my previous supplier.
This is the first time I have ever changed energy provider. I was always concerned about problems that could arise during the transition. I am starting to wish I had not changed.
Can anyone advise me what to do? ??