I've created a website which gets around 5K unique hits every day. It's a free service for users but I've to pay a monthly fee to a third party service provider.
Because my site is free for users and doesn't require users to register it's been very hard to keep up with this guy. If I change certain things, they counter it immediately and make it work. And they use several proxies to send the request, it's virtually impossible to block based on IP.
Please suggest, if there is anything I'm missing that can be done.