I bought this car with 117000km on the clock (ex rental) and the first thing I did was change the oil and filters I have just had the oil warning to change oil
(121000km) it should be good for another 7 or 8 kms
is this normal? the car is in brillant condition and runs perfectly
could it be crap oil on the change?

When you change the oil you need to reset the computer with a program like MultiECUScan.

Unlike a lot of other car manufactures fiat don't use oil condition sensors, so no it will be nothing to do with the oil you put in, you just need to reset the service light