Knocking when braking and pads changed Golf

[Berta]

Hi I bought a Golf and it had a 180 check so I was told before I took it away, I have the car 2 weeks and took it back last week due a knocking noise when braking from the passenger side, it was loud. They then said the pads were loose so sorted it, drove it again and same issue but on lower speeds, they have agreed to change the pads, but could it be something else? It's 3 years old and has passed MOT with no issues on 5/2/18 and I bought it on 11/5/18