Passionfruit Brown Spot is a common fungal disease for this fruit and usually happens in spring and summer. 

Tips:

1. Remove the infected fruit and leaves.

2. Discard any fallen leaves and fruit to help stop the spread.

3. Use a copper based fungicide spray are effective as a preventative measure - apply regularly.

Other notes:

1.  If the fruit is Black and becoming wrinkly it means it is almost ripe.

2.  If green and wrinkly then there is a problem, possibly:

-  Insufficient irrigation when a heavy crop is set or;
-  Most commonly it is the Boron deficiency.  To amend this make a simple boron solution get some borax powder - and mix 4 grams, a pinch, in 4.5L of water. Mix it in. This will treat 4 m2of garden bed. It will last for three years but remember, never use any more than that, because too much can be as bad as too little and will be hard to amend.