IHD and Meter says I’ve used £2300 of gas this billing period

As per the title my IHD and gas meter are displaying a stupid amount of gas usage (£2302)for the first three weeks of this month. (My total gas usage for May was only £16) 

In fact £2000 would be approximately 4 years gas usage for my two bed semi detached bungalow. My online account details show a figure which is as expected of £5.13 gas usage for this month. 
 

why such a discrepancy ? 
also my online account shows readings of 5719 have been sent on 20th 21st and 22nd June

yet my Ihd and meter display 63769.440 under meter reading.

i tried querying with online chat only to be told that consumption varies and basically the meter is a smart meter and will be correct. 
 

Fair enough if the meter is sending in accurate readings,  but if Ovo were to manually read my meter or ask for a manual reading they’d be getting the much higher read. 
 

I did ask if the reading on the IHD is converted at some point to the reading they use their end but was told  no. 
 

My electric meter readings coincide with what I see on my account it’s just the gas which is so out. 

Just to add some more context my electricity supply was interrupted for several hours on 20th June as my supply was looped to my neighbours, and needed unlooping because of alterations to their property needing a meter relocation. During this the main fuse to my electric meter was removed by National grid while the works were completed. 
I wonder if it’s possible that the interruption compromised the information stored in the gas meter as I know the gas and electric meters do communicate with each other 🤔

I have raised a complaint for Ovo to investigate as I was getting nowhere with online chat being told there was nothing the rep could do and no point escalating as I’d be told the same by someone else. No attempt was made to understand my concern nor any realisation that a £2300 consumption in summer for a domestic property where the only gas usage is when I turn a hot water tap on is totally unrealistic anyway for a 3 week period, even saying check my previous bills, just resulted in the same reply that ‘you can’t expect the same consumption every month and there are standing charges too’
 

Just wondering if anyone else has had such discrepancies between the meter reading displayed on their IHD and meter compared with the readings being sent to Ovo ? 
Thanks