Welding of a 4 months old car

I has an accident in March and standard Bank insurance took my car to panel beaters that had my car for month without doing anything to it when i inquired about it i ended they told me the car will be ready in July and i could not wait any longer. I took the car out of those panel beaters with the permission from my insurance. they recommended other panel beaters and i said i only want the Mazda approved panel beaters because they know what they do and is in line with my Mazda. they refused and sent me to their panel beaters. On the weekend i discovered that the bumper is not tight with the fender and when I looked at it inside I saw it was welded. I bought this car in November 2014. I called them this morning and they said they took instructions from the assessor, i called the assessor and he said he made recommendations and didn't tell them to weld it instead of putting the new part. the reason that i was given when my car was away for a month was that they were waiting for a new bumper so what has changed now. it is still the same case but different procedures. I have a bumper that is coming out and a part that is in between bumper and a fender that is missing in my car.