Fidge repair?

What is the law on replaced parts in my fridge that brokedown just before christmas 2016 one that is heh!

I had to get engineer out as didn't have confidance to takle, chickened out. It was repaired through Samsung and was offered no guarantee on parts replaced. ' the fx Group. Net have ignored my emails they just sent receipt of totals and no guarantee. I asked twice for information what was replaced and guarantee they have ignored my emails. I thought UK law was repares were subject to a guarantee of min of 90 days.

Can I demand? Trading standards i am still waiting a reply after a week. They seem as useful as a chocolate teapot as this is not the first time dealing with them with no results.