I'm not bang up to date with the reg's these days, but I think the supplier is obligated to perform a safety check on the meter at least every 24 months. In between times, they may or may not read the meter for billing purposes at their discretion, and the customer may or may not submit their own meter readings. Smart meters change all that and in theory create more accurate and hopefully reliable billing.
Where the meter has died, the date at which you report it failed and the meter reading at that date are the only known facts**. Everything else is assumption. If the supplier has over-estimated your usage, then I'd be seeking a refund back to the last meter read on the date you reported the suspected fault.
** digital meters may store some data which could still be retrievable, but it sounds like you have an old electro-mechanical meter.