Noisy fuel pump & Emmisions light.

My girlfriends car so I dont have all the details so hope this is ok, this may not be the best place to post but if you can read and pass on any idea's you have it would be much appreciated...

Vw Polo twist 1.2L 2003 - gutless but (was) reliable

Following a complete service, filters/oil/plugs the fuel pump was very noisy, then after ~10miles the emmisions light came on.

When taken to the garage this was diagnosed as a problem with the fuel pump essembely, this was replaced.

However the pump was still noisy, and ~20miles later the emmisions light came on again. This time it came with a intermittent problems with idle (revs drop from ~700rpm to ~500rpm and the engine appears to almost stall.) At this point there is a reduced throttle response at idle and also while driving home. This time when taken to the garage they discovered that a "servo hose" was disconnected from the inlet manifold which was replaced.

This did not fix the problem and now we are at a bit of a loss for the case of this...

Its been to the garage again since and all they were able to do is reset the fault codes, no idea on what is causing this.

Thanks for any ideas on what may be the case of this, will be having a look at the car over the next couple of days so any ideas on where to focus would be appreciated.

Steve