Hey I'm stuck at helms deep and I can't get past the part where it's your..

Have eaoden/berethor,idrial,and hadhod in battle and make sure you have these skills,
Berethor:war call,fellowship grace
Eaoden:rohirrim rage
Idrial:gift of grey haven
Hadhod:mountain shield,flames of ruin(optional)
Use mountain shield first then cast aura of the valar on everyone, then use cleaving wound(if you have it) on the trolls(get rid of all 3 trolls and the uruks are easy)
When 2 or all ll of your characters hurt,use gift of grey haven
With berethor use fellowship grace then keep using war call on the trolls,ignore the uruks
With eaoden you can use drain health or rohirrim rage,they both do a ton of damage when he is a high level,until the trolls are gone
Keep using flames of ruin on the uruks till you win(it is almost impossible to miss)

If you're talking about the barttle after the cut scene where Saruman talks I agree with you it's really hard! It took me ages so I decided to stinge on Perfect Mode until I got to that battle. Use Frenzy or Double Attack as much as you can. Arnor Mushrooms mean you don't have use AP's for your attacks. For Hadhod use Spirit Powers a lot because they always hit, same for Eaoden and Idrial. Use Morgul decay to bring a foe's armour to 0. Idrial's Aura of the Valar is good it only works for 1 go though so is Loudwater Fury. For Eaoden use Drain Health and Elegost's Aimed Shot always hits. Good Luck!