Dear I had the same, it hppenned in the month August during the time when I was out of qatar for one month.
I was advised by my friend to report the same in Kahramaa office and I followed. as per advice by the officer, I put the complaint for a faulty meter. Now it has been replaced with a new one. I visited after the replacement of new meter and they told me that my big amount bill will be adjusted and will be informed accordingly.
So please visit the Kahramaa office nearby and submit your request for faulty meter.