If you IP has already been Null Routed then, the only solution that Memset can offer is to wait until the attack has stopped. Once that has happened we will route your IP again and your site will resume normal operation.
If your IP has not been Null Routed or you are experiencing issues because of a (D)DoS attacks, then you should consider enlisting the services of a a company that specialises in keeping sites online during DDoS attacks as they have specific and specialised resources available to resist such attacks.
Some providers are listed here:
Additionally there are various tools and utilities that you can install on your server, or use to route connections through (via DNS), that will offer some other protection.