Incorrect reading

I just got an email from Bulb saying that my payments are due to rise. However, when looking at my account and comparing previous readings to my current readings, it looks like I submitted an incorrect reading for my electricity in March. I have recently submitted two new readings via the bulb app, with photos included but have not received any response.

What can I do to resolve this as soon as possible? I believe I am being overcharged to the tune of approximately £200.