"SE" is Sweden. Even they screw up once in a while. My 89 244 had spot welds that didn't "take" on the backrest frame of the drivers seat, resulting in a lopsided, twisted out of shape seat---a lot more serious than a muffler bracket, as the backrest is an important safety component.

In your case, the bad weld is a lot more troublesome than it would have been for most repair shops. They would have had a torch (or a MIG) on hand, and it would not have been a big deal to stick it back together. Still, you shouldn't have to deal with such a situation---the part should have been ready to go when you received it.

Recently, there was a thread on a similar subject, blaming IPD, for a downpipe with poor quality welds on it, made, I believe, by Starla. It drew a lot of responses.You might want to give that a look too.