Advice needed on Uni changing goalposts

So I'm a 2nd year and failed two modules as I have been suffering depression,

Our university has the standard process that it condones some module failures and not others. And that in order to progress to the next year you need an average of 40, and passed all the modules you can't condone.

I failed 1 condonable and 1 non condonable. My average is over 40.
So since results in June I've focused soley on revising for the 1 I have to pass.
When the resit registration came in I was registered for both resits. Not wishing to pay an extra £200 for the resit I didn't need to pass and had no chance of passing I asked them to remove it so I just sit the 1 module that is Non condonable I need to pass to get into next year.

However one of their junior service assistants replied that I had to resit both and there was no negotiation on this. When I asked her to clarify or give a reason why the normal procedures werent being followed and whether she said I had to pass both, she just replied saying you have to pass both to progress.

Even though this goes against the University's own procedures? Which clearly say I only need to pass the condonable one!

Please help/advise on what to do?

Maybe you missed the deadline for accepting your condoned pass?