Thread loosening

I'm so disappointed with Zara's clothing items. I've bought clothes there so many times not only for myself but my children aswel and for some unknow money wasting reason they all come undone on the seems,hems and really anywhere where there's thread, this is extremely annoying as I spend so much money buying these items hoping it will be better quality but my children's pep creche clothing lasts long. So what's the point?????? Honestly don't know how I always go back to buy more clothes but I think I've finally learned my lesson.