Liner coming loose

[BMW1600]

This is getting frustrating, the liner that was put in when the pool was new, never came loose.
We had a new liner installed last year by a different pool store, this new liner will not stay in the track.
they have came out several times to put it back, but it’s not staying.
my question really is, why won’t this liner stay locked? Was it measured wrong, is the liner to big or small?
Any information will be helpful
Thanks

 

[cowboycasey]

Welcome to TFP

Can you post some pictures of what is happening, maybe someone will see them and be able to help... What is the company saying about it? Is the original company still there, can you have them look at it?

 

[kimkats]

Did they use "liner lock"?