Question for UK train nerds. (Please re-toot to you UK train nerd friends, thank you!)

The question is simply: what rights to compensation exist for such a shitshow of a journey other than "you arrived x minutes late so we'll refund y% of your ticket price"? And how do we go about getting it?

My partner tried to do Cambridge –> Leicester –> Loughborough today by train. They left Cambridge on time at 12:00 but there ends the good news.