How can I figure out why my electric bill is so high?
By FAR the best bet for billing questions and complaints is to call your POCO (power company).
In my area they take high bill complaints very seriously and will send a representative out quickly. 

Also, things like this are absolutely NOT grounding/earthing issues. It is possible that it is a neutral problem and the grounding has become part of the issue that way, but grounding has nothing to do with the day to day operation of the electrical system.