Have you had it diagnosed as such by someone who knows what they are doing?!?!
Many faults are attributed to the device which can be caused by other bus devices. The only way to really know is often to disable other devices (remove them from the bus) so that the real fault can be confirmed.
If you do swap it, you will need to budget for the reprogramming of the car too. Make sure you get someone who knows what they are doing to ensure that the car mileage is preserved, as that i s held in teh BSI along with the instrument cluster. It *should* take the mileage from the cluster, as it uses the higher of the two values.
Its possible to find yourself a second hand unit from another vehicle as long as it visibly looks the same. It can be cloned the original unit to work on your vehicle without any problem much much cheaper than giving your unfriendly Peugeot dealer hundreds of pounds.