Mot pass?

[marvie]

Hi, last year my car had an advisory on mot certificate that front and rear ball joint dust covers were worn. The guy at the garage told me not to worry about it for the time being. This year I had taken my car to a different garage for the mot as they had done some other work for me. I was half expecting it to fail due to the advisory from the previous year. When I went to collect the car they said it had failed, but due to the windscreen wash jets not working, which actually were fine, just out of water, as I'd emptied them on way down. I filled them with screenwash at the centre and they passed it. No mention of the dust covers. That was about a month ago. Yesterday I've noticed a creaking in the car going over speed bumps. Would they have passed the mot if the dust covers were that bad? Or could it be something else, car feels fine to drive otherwise. It is a 2006 polo. Any advice would be appreciated. Thanks