i been posting about the same problem on mine mate. mine is deffo drinking more fuel, and it seems to be since the fuel injection software was reprogrammed in my case. im having to take it easy just to get 300 miles on a tank at the moment. was more like 400 before i thought. car is booked into renault wednesday morning yet again as a result now, as 307 miles on 10.4 gallons is remarkably sh*te for a 1.2 16v, and is what i got from the last tank - think thats 29mpg!
let me know if you get it sorted fella