Cable disc brakes feel spongy after a pad change

Had exactly this. It turned out to be the cheapest part in the whole system.

Bring it on Thursday and we will have a look together.

A drop of grease on the threads fixed mine.

Take a short video with the sound on, it helps a lot with diagnosing noises.

If it is under warranty, go back to the shop first.

Do not overtighten carbon parts. A torque wrench is worth it.

I would replace rather than repair at that price.

Clean it properly first, half of these problems are just dirt.

There is a good guide on this in the Articles section.