I had a peugeot in a while back with the exact same problem, been to a few garages and they all said pump.
Spoke to Autologic and there was a TSB for this, filter was modified and was recommended to use a dealer part, which was Mann & Hummel. I replaced it even though I couldn't see any physical difference and it was only an element, so was quite sceptical, anyway it did the job, been perfect since.
Not saying it'll be same for this model, but worth a try.

Chris