Bluespark tuning chip

[Fiat2004]

I have purchased a Bluespark CR for Punto 1.9JTD 86 to improve my economy as I have average 48mpg out of 56mpg factory officially. Now it is 3 weeks of test with one week left money back guarantee. I was quite disappointed with mpg result it seems not improve here is my timetable 3 weeks work is total 1,236 miles calculated by petrol station not trip computer.
48.6mpg countryside first week
47.1mpg countryside second week
49.7mpg dual carriage plus countryside on the third week
Yesterday last fill up 48.2 mpg countryside

It looks like the chip doesn't make any difference for £79.99 but the power is improve between 1,400 to 2,200 rpm more downlow torque.

What you think of Bluespark is there option better out there? Would it remap a better or just send back get my money back guarantee? I have hear on Top Gear said engine modifications are complete waste of money I think it was blue Renault MPV.

[nick_dastardly]

As well as bluepsark TMC also do a tuning box that is well thought of on abarthisti forum.

Would have thought these would decrease mpg though, unless you're very restained on the pedals...