Email for official complain

I have already wrote here and to the customer service but the answers that the staff member was absolutly not acceptable. He didn't put any effort to resolve my query/problem, he didn't listen and I had to wait a week sometimes to have a pointless answer anyway. I would like to make an official complain, where can I find an email different from the customer service?
I spent lots of money in this product and the service is riddiculus.

Many thanks