You need to press for a replacement meter and probably the IHD as a matter of priority. Otherwise your bills will be estimated, which is less than ideal, but might be exploitable.
start working out from previous years what you consumption was in the same periods, so that you have some facts if you need to challenge what the company eventually come up with.

Be firm and point out that they have licence obligations to provide accurate metering.
Current Eon Next customer, ex EDF, Zog and Symbio. Don't think dual fuel saves money and don't like smart meters. Chronologically Gifted. If I offend let me know by private message, but I’ll continue to express my opinions nonetheless.