Not sure about rear wipers & number plate lights (ie wiring loom related stuff) but the boot handle microswitch failing is one of the few things that crops-up regularly on the Panda. Seems Fiat carried on using the same component in the 500 even though it was poor in the Panda. 
I've been down there today getting my Stilo serviced, saw a ChaChaCha Azure 500 parked round the back either yesterday or today - maybe yours?!
They're a good bunch at Pewsham (KTA), it's only the 2nd time i've used them but the price for this service & a couple of other bits was cheaper than my local independant & both times i've been there the car has been washed before being handed back. Very impressed. Not so impressed with the rain on the way home that's made it look a right mess again - wish we had a dealer that good on our doorstep - it's about 50 miles from me
Liam
Ok, got the car back today, all fixed.
The bets were accurate; yes the loom was broken as suggested.
The original Fiat part to replace would have cost £450 just for the loom!I made it quite clear I'm not paying that!
I caused a bit of a stink, warbled on about 'loyal customer', 'shouldn't happen to a car this age', etc, etc. The Fiat dealer managed to get authorisation for Fiat to pay the majority of the repair to the loom, with myself paying some towards it also. Total cost to me including VAT as £95.21, which I'm a bit happier about.
This was KTA Fiat in Chippenham, Wilts, which are at the bottom of the hill to where we live and have used them for quite a number of years now on my car and my wife.
Pete
I've been down there today getting my Stilo serviced, saw a ChaChaCha Azure 500 parked round the back either yesterday or today - maybe yours?!
They're a good bunch at Pewsham (KTA), it's only the 2nd time i've used them but the price for this service & a couple of other bits was cheaper than my local independant & both times i've been there the car has been washed before being handed back. Very impressed. Not so impressed with the rain on the way home that's made it look a right mess again - wish we had a dealer that good on our doorstep - it's about 50 miles from me
Liam