Looks like the squeak has returned - because the thermal paste has burned away with the heat of the turbo. The master technician has been extremely helpful and provided irrefutable evidence that the turbo arm is moved upon first unlock and that it is the charge actuator that's squeaking. The charge actuator has partially seized which is why it's squeaking.
Even though the master technician and the warranty manager at the dealership think the turbo needs to be replaced, the extended warranty claim was rejected because the only status option to select for the part was 'failed' - and that is the
problem because the part hasn't failed but it is failing and needs to be replaced. I'm still waiting for SEAT UK to contact me to confirm whether the decision not to replace the turbo has been overturned. The master technician said that if the
problem had been discovered during the three-year warranty, the turbo would have been replaced because he would have the justification and authority to do it. He said to me that extended warranty is a different game because he has justification but not the authority to replace the turbo. I logged a formal complaint with the other dealership who didn't get to the bottom of the
problem during the three-year warranty period and they've said that if the master technician at the other dealership can provide evidence of his diagnosis, then they'll replace the turbo themselves at no cost to me if SEAT UK's final decision is not to replace the turbo. Result.
If anyone's car makes a similar noise when unlocking or when turning the engine off, it'll be well worth checking whether the turbo actuator is starting to seize. The noise when turning the engine off is new and only started happening a few months ago - which was another sign that the seizing was worsening.
