I also had same issue...I sent mail but got no reply.. Someone
purposely generated invalid clicks on my webpage ads but my account got
banned without any warning !!

I Dont Understand Why Account Permanently Ban Punishment Is There As
Every Time Publisher is Not Responsible For Generating Invalid Clicks !

Some Suggestions : Why its not like :

1) Generate Warning Mail And Inform To Publisher..Filter Invalid Clicks
And Dont Pay For That

2) Goin Further If Invalid Clicks Continues Make Accoutn Balance To
Zero

3) Display NO Ads where invalid clicks generated ie. javascript code
will generate no Advertise for that specific webpage URL on which
invalid clicks generated this is equal to Webpage Ban but option open
to display ads on other websites / webpages..

4) Last Option To Ban Account If Invalid Clicks Continues...

Dont You Think That This Will Keep Happy To All Adsense, Adword
Advertiser And ads Publisher  ?

Is is fair to ban account permanently without any Notification or alert
as anyone can do it with anyone account ?

If  it is applicable only for small websites or for those who dont have
much trafic on there websites then why Google Approve such applications
?

-MAHESH