Popped ball joint when putting in reverse.

[Millie1607]

Hi total novice here. Berlingo multispace 2005 1.9 diesel
First go at driving a car and something went pop and was stuck in reverse.
Bf looked it over and I'd popped the ball (5) out of the joint (1). 
He replaced the ball as it had chips missing out of it. It's not been used since june (apart from getting to mot station and reversed out of the yard where its kept) when it was replaced. He had to move it the other day and it's popped out again.
How can I stop this happening? Do I need to get something else changed/replaced?
I've got my driving test at the end of the month so I need to sort it as don't want to breakdown with kids in the car. Picture from when it first popped out. Thank you.

[Johny555]

Its not a ball joint,looks like gear linkage, think it needs replacing,

[Partner1981]

the linkage is cheap in the bay and quick fix for everyone just need a plier and long arms .

[ffrenchie]

Once you've popped you just can't stop, like Pringles Yes it needs a new one.

[Millie1607]

Thank you. I said to him the linkage but he said no. I will get them ordered and just hand them to him when they arrive.

[Tomcat3]

I think your boyfriend had been telling you porky pies, buy the bits with his credit card lol.

[V6BOY]

Very common worn selector linkages should feel like night and day when changed.