I just joined here  and im really happy with my fabia even when the problem starts lol  

The problem i have is a hard one to describe  ,most of the time it drives fine and well but it will sometimes  while doing 60 in third 70 in forth and rarely 80 in top gear  it just dosent have any boost  so starts to lose speed  ,it just dont have any boost ,dropping gear dont help  if it turn it off and bump it itll give me a wee second or 10 of boost  then no boost   but other times it drives perfect  

I had it on  a computer and it said 2 injectors  but i was told its a bad job to do   just wondering if any body has came across this before 

It sounds like overboost is forcing the ECU into limp mode, I assume it's a PD100 and it isn't remapped, if so it's likely to be the VNT mechanism sticking at full boost long enough for the ECU to reduce fuelling.

okay can you tell me what the vnt is please

@mikeymikeyp - Variable Nozzle (sometimes Vane) Turbocharger. It's a device that varies the force the exhaust gases apply to the turbocharger inversely to engine speed. Sometimes this gets stuck in a low revs setting, and makes the car overboost at higher speeds. Someone nearer you with VCDS (check VCDS forum) may be able to confirm that for you.