The fabric that holds the seat back and bottom tucked in tore.
The repair shop can not use the cardboard strips as thier sewing machine will not go thru it.has anyone used j channel or something else?
Thanks
The fabric I'm talking about is hidden and its on the back of the seat cushion and bottom of the seat back

I know this is not what you want to hear but, take it to a different upholstery shop. If the shop you are using doesn't have the proper equipment to make the repair then they won't have the expertise/equipment to do the job correctly.

Sure there are ways to work around the problem but why not do the job correctly to begin with?

I fought with cloth seats I had made for a W114 for years before I finally threw in the towel and had them re-done properly.

Wood slats, cardboard strips as wedges, aluminum rails, pop rivets, stiff plastic rails, etc., I tried them all. The closest I came was pop rivets through the outer lip with a strip of Lexan on the front. Lasted for a bit until the fabric tore.

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