That's just the price of diagnostics. If you read further you'll see that the full repair price is £169 + shipping. But yes, that confused me at first as well. They replace the GPU and use lead solder.
The sad reality is there doesnt exist a reliable source of _real_ new replacement GPU chips. Almost every single chip from china is either a pull from dead laptop or old stock(1). Chinese counterfeit markings, clean them up and sell as new.
The absolute best case scenario is you get really new old stock and it will survive at least 2 years, but in reality it will most probably be a pull from recycled trash with week-month lifespan.
https://www.youtube.com/watch?v=OogV7pbqEGQ
1- Nvidia chips were ALL factory defective (bad underfill between die and bga carrier), every single GPU at least up to FERMI has a limited life span dependent on thermal stress. Nvidia had to issue huge recall and restart manufacturing of ancient chips with fixed underfill formula - they only did a limited run for select partners (Dell, Apple) and those chips are pretty much _gone_ from the market.