Thank you for getting in touch!
Based on your usage I can appreciate where you concerns are coming from. Can I asked if you've carried out any tests within your household to test the accuracy of your meter?
The '10L test' or 'bucket test' is a good place to start. Your hot water meter records decilitres, so it should be increasing by a factor of 1 for every 10 litres of water that pass through the meter. You can run this test by taking a reading of your meter, filling a bucket up with 10 litres of water, and then taking another reading of your meter. If the meter has increased by a factor of 1, then your meter is working correctly. If the meter has increased by a factor of more than 1, then your meter may be recording your consumption incorrectly.
If your meter is recording your consumption correctly, then it is likely a case of the hot water system having some form of fault/leak.