I have been asked to look at this for you. Have they declined special curcumstances request?
You can always appeal any decision of a University. That is probably the best option at this stage.
However, you need to convince them that shingles amounts to an exceptional circumstance. Ill health, per se, is not sufficient. In fairness, there are many conditions that may stop a person going to work but they do not necessarily prevent them from working on a thesis at home. I don't know whether you are in a position to show that it was impossible for you here or not? It depends what your doctors will confirm.
An additional problem here though will be that you don't seem to have told them until after the deadline which is not the best place to start from I'm afraid.
Its never quite right to say that deadlines are fixed. There is always room for variation for something like a bereavement or an accident that literally leaves a person in a coma etc. Nobody is going to argue with something like that.
You may well be able to reach that standard but thats the test for which you are aiming.
Can I clarify anything for you?