who can help me increase my giveaways limit?

None of us. You can continue waiting for support, or do it the slow way, giving away games one at a time (assuming you don't have three deleted slots already)

Why would you want to increase it if you do not giveaway nothing?

http://www.steamgifts.com/about/faq
"We limit the number of gifts a user can create for security purposes, and to prevent a new user from potentially posting a large number of invalid gifts to the site. When you create giveaways and your gifts are received, this number will increase, and you'll be rewarded with the ability to create giveaways with a greater number of copies, or more simultaneous giveaways."

Give away some games. Support probably won't give more slots to a person who hasn't done any giveaways, just sayin'

Submit ticket and wait. Wait until your number is called. At least online you can walk away and still be in line.

1 week... Long long? I closed ticket after 5 month without reply...

long long time

Wait a second! We all love you long long time! Now where's the hidden GA!