To play devils advocate, any evidence you had should have been provided at the start and as others said, depression is not a free ticket. Tbh it falls pretty low on the list of special circumstances and I say this as a sufferer (compared to deaths, being hospitalized your house burning down or being stuck halfway around the world without a passport) Special also tends to mean 'unusual' but in your case is long term and ongoing.
If you're already studying in the least stressful distance method possible and can't break 25% with 2 tries they'll have likely judged that it's unrealistic for you to continue without starting again from scratch.. Past a point you need to be able to complete and pass. depression or no :/
Likely unrelated but least year my uni got hit with new rules, only 1 resit allowed, not 2, end of