Wrong Boiler!

30 months ago we urgently needed a new boiler in our large 4 bed detached bungalow. The Biasi was always unreliable and I was regularly having to change parts in it to keep it going. The cost of a service engineer was not affordable so DIY was called for with that boiler. (I had, many years ago been an industrial heating engineer). Help Link were advertising so we had their salesman give us a quote which was not cheap but installation was available quickly. ( My Wife has just left hospital that January following a very serious operation). Also the 10 year Bosch guarantee was attractive. A Worcester Greenstar Junior 24 was installed quickly, but the water delivery was very hot at 55 C. Don't ever try bathing in a bath of water at 55degrees C !. We were advised the the temperature was not adjustable. Installer stated that earth wire, cross bond to gas meter was impossible and not really necessary. After many months of correspondence,. Bosch visited and advised us that the wrong boiler had been installed for our house as the model supplied was designed for small flat. The earth wire to meter was a required safety requirement. An earlier posting on internet brought a response that Help link would investigate. This, only a few days after a letter was received from Help Link, 'Closing their file'. Their own engineer had also stated that the wrong boiler had been installed. I ask the questions, 1.Why ever would Bosch make a boiler so badly designed that the temperature of water delivery was not adjustable? ( This model ceased production about the time ours was installed !) We were advised that it no longer complied with safety updated standards). I wonder what is the truth. Why did they install that model which was clearly inappropriate for the house? My patience is at an end and as the claim sum involved is under £5000, legal procedures are very cheap and straight forward. I hope that I will be spared the time wasting of taking it that far, but if needs must..... One thought though, supposing we had a fire, God forbid!..... Needless to say, I would neither recommend Help Link or Worcester Bosch.