You can stick the ear back together with superglue.
To catch her, bring the whole lot in and be as calm and gentle as possible. No chasing them about as they just get stressed and you'll never catch them.
We have a pen permanently set up (hurdles) and funnel them towards that. We use electranet, not electrified, but I wouldn't advise it unless they've been used to it before. You get the idea though - they'll go into a wide area, but not directly into a narrow one such as a small pen, so you need your system to start wide and narrow down towards the pen at the end. If you have a spare hurdle, put it over the top of the catching pen to stop them jumping out.
If you have a building they will go into readily, get them into that, then set up the pen in one corner. Failing that, get them in the smallest paddock you have before aiming them at the pen.
Really, you will have problems catching wild Soay, so it's best to get them accustomed to feeding in an open pen, then being used to people milling about amongst them, before you shut them in with a gate across. This takes a few weeks - sorry no help with how to catch your one with the damaged ear.