Long helical springs across seat frame

[RTU]

I'm making new seat cushions for a couple of wood frame chairs that have long helical springs spanning the width of the seat frame instead of webbing or front-to-back no-sags.  I've never seen this before and wonder if anyone else has?  I suspect it is a DIY thing.
The springs are a bit saggy and because of the way they are anchored (in recessed holes in the frame) I don't think I can remove them without damaging the anchors and/or the frame.  The client is okay with leaving them but I'd like to see if I CAN replace them.  I just haven't found anything like them through my suppliers or on line.
Anyone know anything about this style of springing a seat? 

[MinUph]

Pictures would be helpful.

[RTU]

I tried to attach a photo but just kept getting error messages.  Will compress the photo and try again.

[kodydog]

Try using google photos or the like. This forum is not set up to attach photos. Let me know if you need help.

[baileyuph]

Probably doesn't matter because you (doing the job), know it isn't the best spring solution.

So, depends on customer solution; go with his idea or explain that webbing would probably be cheapest
solution.

Good luck on this one, basically not really your problem in the end.

Doyle.

[RTU]

Thanks, baileyuph.  The client and I have decided that a firm cushion will provide the support needed to counter the relaxed springs and I will install a protective decking pad over the springs (secured with velcro over front and back springs) to avoid marking/denting the new cushions. 
Webbing was my first thought too.  Sadly, it is not really an option because it would be visible whether installed on the top or bottom of the seat rails, not to mention that there is no front rail. 
I am going to try to make a photo available through Google Photos.

[RTU]

For those who want to see a photo:
https://photos.app.goo.gl/VUfGhgmJfRlXiw6v2

[sofadoc]

In your first post, you speculated that it might be a DIY thing.

It's a UK/European thing. Might be a Parker Knoll chair.

If you join the Upholsterer's Friendly Forum on Facebook, you can easily post a pic of that chair and get all the answers you want about it.