2.0TDI Rev Counter, Startup and running issues......Bluefin?

Hey Peeps!

Im in need of your help once again. It seems my car is having a midlife crisis.
I have an '06 Audi A3 2.0TDI (140) DSG bluefinned!

I have just had the cam belt changed as I have reached 85,000 miles. Everything seemed fine after the work except there seemed to be a sudden considerable drop in mpg after getting it done. I thought the belt might need running in.

Now this Sunday, I tried to leave our church carpark and low and behold after turning the ignition on, the rev counter suddenly starts going berserk and jumping up and down all over the place. The engine would try and start but would not ignite. The yellow coil was flashing at me which ive read means something to do with a failure with the engine management system.

My thoughts jumped immediately to getting rid of the bluefin map and restoring it to original. I luckily eventually managed to get the car started and running somehow. Although it was far from being fine on the journey home.

I got home and turned the ignition off and then tried to restart the engine on multiple occasions - there seemed to be no problem?
I then got the bluefin unit and restored the original map to the car. Everything was fine with the car again.
So this evening I decided to put the bluefin map back on. Hell it was so noticeable that the bluefin wasnt on the car.

On my way back from Tescos ten minutes ago, I come round the corner and the engine completely cuts out on me and then the rev counter goes mental again same as before. The P-R-N-D-S also starts flashing at me. I chose to put the gear into N and cruise to a safe parking place. I tried restarting but had no luck. Luckily I had the bluefin with me due to the recent issues so I immediately restored the original map again. The car started fine and I drove home.

Question is....why is this suddenly happening now?
I have had the map on for a year - on and off due to servicing and Ive had no problems at all. Does anyone have any answers?

Any Constructive feedback is always greatly appreciated.

PTTM - Happy New Year

Thanks everyone - Ant, I tried looking at the errors through the bluefin. I plugged it in and went to extras and I only saw immobiliser. How do I get it to show me the fault codes?

Guys I forgot to mention. There were some error codes when I had VCDS plugged into my car when Hazzy Dayz were fitting bluetooth into it.

00716 - Air Recirculation Flap Positioning Motor
01403 - Glass Break Sensors, Rear

Any ideas?

Btw, anyone know why I have a sudden drop in mpg as well after the cambelt change?
I was getting 55-60 and now im averaging 37mpg most days. My driving style hasnt changed at all.

Is it the weather?

Right things have now gone from bad to worse. Obviously no garages are open over the christmas period so i have had to use the car. The car doesnt start very often, it just ticks over and doesnt turn on but when it does it starts with the Emission light (engine icon) on and it stays on after starting the car. The coil doesnt initially light up however after 2 minutes of driving that starts flashing at me. The car no longer revs over 3,000rpm and if i slip the car into neutral at any time whilst driving the engine will just completely cut out. It is also just cutting out randomly whilst driving. Anyone got any ideas?
I am gonna take it back to the garage who did the cam belt change, however im afraid they will say it wasnt the fact they fitted the cambelt wrongly it was something else so they can charge me. What do i do?