First of all, write to the Governor.  You should get a reply to your letter within 28 days. 

If you are not satisfied with the reply, you can contact that prison’s Independent Monitoring Board (IMB).  The IMB is an independent panel of people from the local community who are there to keep an eye on how the prison is run.

You can also write to the area manager who covers that prison. 

If you are still not satisfied you can write to the Prison Service Headquarters and/or your MP. 

Prisoners who have a complaint can request an interview with the Governor or member of the IMB.  If the complaint cannot be resolved, they can contact the Prisons and Probations Ombudsman.