Living Well Today Magazine LWT magazine failed to return phone calls, respond to emails, etc: They failed to run the correct ad in the magazine, for which they nonetheless billed me. The incorrect ad was run in subsequent issue Chatsworth, California

LWT magazine failed to return phone calls, respond to emails, etc: They failed to run the correct ad in the magazine, for which they nonetheless billed me.
The incorrect ad was run in subsequent issues.  They have refused to acknowledge that they have  committed a material breach of contract by so doing these things.
A summary of my issues with LWT magazine follows.
A brief summary of the
facts in this case follow.  I sent LWT a June 19,2012 letter  advising them to cancel the remainder of the contract  and to consider it null and void because LWT failed to print the ad that I  had approved.  LWT failed to respond to  voice messages left with LWT and they failed to respond to emails that I sent.  It has been a pattern
with LWT that they fail to respond to phone calls and emails.  Moreover, they failed to print the correct ad  copy that I provided to LWT. 
In addition, in December 2012, LWT, further breached the terms of the
original contract by ignoring the June 19, 2012 letters request to consider
the contract null and void. 
Specifically, in December 2012, LWT sent a packet of copies of the monthly ad printed in
the LWT magazine through December 2012, to Stephanie OConnell.  In every single issue, the incorrect ad was printed.  At this time they have retained legal counsel and have escalated their insistence that I pay them additional money.  I have asked for a refund of the amounts I paid on May 30, 2012 & also in August 2012.  They insist I owe them over $600 at this time.  I have advised them that if they continue this insistent demands for me to pay more money, I may consider this harassment and abuse of process.  I am awaiting the response from them to a letter I am mailing on Jan 2, 2013.