There is no problem with pirates gentlemen.
First off, most multiplayer games disable the pirates, to allow for a pure strategic experience. If you don't like them, disable them. Period.
That being said, if the pirates are defeating you easily, you are doing a wide variety of things wrong. In multiplayer, the pirates are used to level-up titans, which become much more powerful as they level. Many of the titans can defeat the pirate base with the help of just a few supporting frigates/cruisers. In the rare case where pirates are enabled in Multiplayer, players frequently bid to send them to an allied player, so that they may be used to level cap ships or titans.
How to defeat the pirates with ease:
1) Kill the siege units, then leave the planet well.
This can be done easily with a handful of frigates. Once the pirates are done destroying your buildings, they will leave (since they have no planet siege), and your planet will be intact.
2) Build a bigger fleet.
The pirates always send a fixed number of units, depending on level. A larger fleet will defeat them every time, easily. This doesn't mean building 7 frigates instead of 3. It means building at least a couple of cap ships, and 40-50 frigates, which can be done even on tiny maps.
3) If by some strange miracle you manage to do tremendously badly in expansion, and you can't afford to lose structures or build a fleet, you can still beat the pirates. Simply build two trade ports linking your planets. The pirates will chase the trade ships first, and can be killed easily by a relatively small fleet while they are doing so. You should never do this badly while expanding, but even if you do, the pirates are still beatable.
4) Pay more bounty than the other guy.....
If you can't manage to do at least one of these things, you don't deserve to beat the pirates, or any other player for that matter.