Thanks a lot for your responses. You see in Vanilla and most other mods you can just siege attack to victory. It's kinda cool that the only way you can win this battle is to starve them out!

Most people have said to pin them with Triarii, but I have found they die quite easily, generally and conventionally how I play I use the hastati and principes if needed to pin enemy and then use the triarii to protect my flanks from cavalry attack. If the enemy are stupid enough to use their cav to attack a point on the flanks, the triarii will cut them down, leaving them able to the sally behind the enemy lines and crash into the back of the enemy, together with my cavalry who i use to sweep up any missile troops. So woudl you recommend I put the triarii in the centre of the lines or target them wherever the Gaestae attack.

Cheers