Bulb Energy - bogus reviews on TrustPilot?

I joined Bulb when I moved house in August.
The switch was great, and had no problems, except that I couldn’t enter my gas meter readings. The readings were not accepted because they said it was too low. So I uploaded photos, more than once. The readings were never updated, only with estimated ones.

A few days ago I received an email telling me that I have used over £4000 of fuel since September, which is impossible.
I have emailed and had no response, I posted on the community page, and was told to talk to the company, which I have tried, but I have been unable to phone because of the nature of my work and the limited times they are available.

I was banking on them having some kind of customer service on a Saturday, but they dont.
Since I have had no reply to my emails, and haven't been able to

I cancelled my direct debit because I was afraid they might try to take a very large sum of money from me (which I don’t have), and now I have an email telling me to set it back up if I am staying with Bulb. I wont do that until this mess is fixed.

My flat is a small, compact, internal 2 bed flat with gas central heating, which I barely need to use as I get lots of heat from the other flats. It is also a new build, and I am the first occupant, hence the low readings on the meter. I do not understand, however, why they accept the electricity reading, but not the gas reading. I am the sole occupant of the flat, and I have only just started using the heating in the last week or two. The boiler that I have, only heats up water as it is used. So really, there is little being used.

There is no way, even in my old flat which had economy 7 and very old storage heaters that I would use over £4000 worth of gas!