The ultimate goal in addressing issues should be to ensure any changes your school has made are not detrimental to you and you still receive the course you signed up to, as far as possible in the here and now.
Where you feel this is not the case, you should talk to your school at an appropriate level; this could be your Module Lead, Course Director or Head of School, starting with Module Lead and escalating if needed. There could be an issue that your school has not thought of so it could be helpful for them to be made aware, in order for them to make appropriate changes.
You can make contact directly with your school and the people listed above or you could use your course rep or faculty convener, or raise the issue with either the Undergraduate or Postgraduate Education Officers, as appropriate to your level of study, although it is worth noting that they are unlikely to be able to deal with your case on an individual level, but will be able to raise common themes with the University. If you don’t know who your course rep is, contact firstname.lastname@example.org and they’ll be able to tell you.