My 2001 a4 with only 30k on it has upholstery sag everywhere. It seems no glue was used anywhere. Suggestions wanted beyond expensive upholstery shop?

 

This place sells the fabric you will need. It is about as close as you can get. I have been told personally by two upholstery shops that they could get any fabric like that because it was foreign. A load of bull in my mind. But this fabric is cheap and already has the padding adhered to it. They also sell glue, not sure of quality though.
Flat Knit Headliner

 

I have the same issue. 3M sells upholstery adhesive spray. That's my plan.

 

Who doesn't have the dreaded sag.... It makes me so self conscious when people get in the back of my car......(sad face) 3m 90 spray adhesive is super potent if you want to try it. It is very very sticky so be cautious and careful with it.