Hi,
I'm new to this forum, however I do work within the complaints department of one of the "big six" energy suppliers. (the actual one shall remain nameless)
I don't really have any advice on a standard price for your property. The main reason being all properties and appliances are different, number of radiators etc, so making a comparison between properties is very difficult, a boiler that's past its best for example could play havoc with your bill. However, £237 per month is quite alot and far more than I would expect.
In reference to the bill you have, I would suggest a few simple checks that you can perform yourself.
Firstly.. Check the meter serial number on your bill is the same as that on your actual meter. Also look on the meter for a sticker or label indicating the meter has at some point been changed.
The reasons for this are mainly down to 2 things...
1 there are 2 main types of gas meter. a "4 dial" and "5 dial". As the name suggest a 4 dial meter will have four numbers in white which are your reading (also 2 in red but these are not relevant). This meter measures gas per hundred cubic feet. A 5 dial meter has 5 numbers in white (and 3 in red, again not important) and measures in cubic meters. Therefore, each unit recorded on your meter will be worth a different amount dependent on the type you have (or the type they think you have) 1 unit recorded on a 4 dial meter will cost you much more as that represents 100 cubic feet of gas, rather than the 1 cubic meter a 5 dial would record. If you have a 5 dial meter and the company takes these readings and calculates your bills based on a 4 dial calculation, your bill will be huge.
2 Meters, like all things need replaced from time to time and have a lifespan before they need to be replaced or "recertified". This is not a task carried out by your supplier but rather the shipper of gas to your property. (95% of the time this will be transco) They carry out the change and inform the supplier after it has been carried out, but occasionally these details do not get thru and the suppliers records are not updated. (this is more common than you might think) going back to my first point, 4 dials are older meters (identified with a 6 number serial number) and are most often replaced with a newer 5 dial meter (these have a longer serial no of about 13 numbers, usually starting G4....) If these details are not picked up, you get the above scenario.
Secondly,
How much have your payments been and have they sent a bill in that time? have they read the meter themselves? I ask these as for such a large amount, your meter may have "overcycled"
This means... when your meter records usage (starting at zero for easy counting, and using a 4 dial) it goes
0001, 0002, 0003 and so on till it gets to 9999.. at this point it goes back around to 0000 and keeps counting. Depending on your readings, they may think, or their records might indicate, you meter has overcycled. (for info once round a 4 dial dial meter is easily 8k and over on new prices) If they have overestimated your bills previously, their system may be so far ahead it thinks you have gone past the 0000 point, when in reality, you haven't.
Thirdly,
Make sure the MPRN (meter point reference number) on your bill actually relates to the property in which you lived. This should be shown on your bill and by phoning transco you can confirm if this is correct. Although, this last option is unlikely to be the case and would pose more questions than answers at this point.
That should be enough to get you started, let me know how you get on.