Hi all,
I recently had this problem on my 2013 (63) Punto GBT. After visiting a number of vehicle specialists and electricians for their advice they came to the conclusion that it was due to the moisture build up within the cluster, which I understand is a common problem.
I decided to take the problem into my own hands. I removed the unit from the vehicle and dried it off with a towel completely. I then began to dry the unit out with a hair dryer, even removing the bulb mount and drying the inside of the unit out. I progressed to seal the unit with electrical tape to ensure no water/moisture could get inside. When fitting the cluster back onto the vehicle I also applied a few layers of electrical tape to the connections.
This seems to have resolved the problem, fingers crossed it stays like this.
I hope that this helps!