Gujarat Gas — Heavy amount of bill received for month Feb-April 2017

Website: gujarat

Dear Sir,
I am timely paying bill of Gujarat gas since 7years, my customer ID is[protected], We get minimum bill of 180-200 rs for consecutive three months then in March I got massive bill of nearly 1596 rs,
Why so much bill without high usage?
How bill was created?
Which unit was accounted for last four month?
Dear sir, please do needful to get money back and give justice.
Regards,
[protected]