E5: Heart of Darkness Problem

I'm having difficulty defeating one of the later missions in Heart of Darkness - it's the clean-up mission after you defeat the homeworld sentinel in the sirgil system. I can't remember what it's called, but it's got me beaten.
Currently, I'm flying a Weave Support Carrier, heavily modified with shield upgrades, hull armour kits and loads of other stuff. I also have 3 Terran Missile Cruisers, a Terran Communications ship (for the mines) and a battleship. I used to have an invincible-class carrier, but that got destroyed destroying the first planet killer. But anyway - I keep getting killed by the deathbringers and star destroyers in the Risa system, no matter how hard I try, I can't cause enough damage from long range and I always get in deep trouble going up close. Anyone care to help? Anyone completed it yet?
Cheers

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As I was walking through earl's court, into a pub i was lured
Where a nosey pomme said "where you from?" as i downed the amber fluid
I said get it straight i'm an aussie mate and i'm looking to get plastered
But the beer is crook and the girls all look like you you pommie... grandad.

I took the alien technology route. Capturing a star destroyer with a terran carrier, I used the star destroyer's seeker drones to kill encountered star destroyers, deathbringers, planet killer and home planet. Unfortunately, the viral missiles and space mines become less useful because they have such a low cap limit to them. (Pity.)