Competitor app using Our App Name in their Keywords

Ask Apple about it via the iTunes Connect 'Contact' Us' tree...Feedback and Concerns.

Good luck.

Well, is it really a violation of anything? Here is the guideline:

2.3.7 ....... assign keywords that accurately describe your app, and don’t try to pack any of your metadata with trademarked terms, popular app names, or other irrelevant phrases just to game the system. .....

If your app is a "popular app name" and if "metadata" includes "keywords" then it is a violation - two "ifs" make a weak argument. Under certain copyright or trademark restrictions you might have an objection.

Another approach is to 'bluff'. Contact the other app and tell them that unless they make a change - and quickly - you will report the violation to Apple and have their app removed from the store.

A third approach is to join them. Add their app to your keywords.

Somebody is doing that to me too. For a while they were using my actual app name too and adding "Pro" to the end. Apple has a link to report such things but I can't remember where it is. Apple put us in touch and told us to resolve the issue. After several profanity-laced emails from him, miraculously he agreed to change the name of his app. I'm fairly certain he's still using my app name in his keywords (my app name is fairly unique) because his renamed app shows up second behind my app when you search on the name.