Just wanted to give a shout out to GB Foam who supplied out replacement foam for our Troll sprung cushions.
Like many we found the original sprung cushions too firm for sleeping on (even with a memory foam topper). However the front dinette cushions, non sprung, were a lot more comfortable. I did e-mail Hymer requesting the specification of the foam but did not receive a reply. Fortunately the foam in our VW camper was very similar and a telephone call to the converter, provided the information we required. 39H from GB Foam was what we needed.
Using GB's website was simplicity in itself and I followed up by posted a tracing of the curved end of the existing cushion as a template. Within a week the replacement foam was delivered so all we needed to do was unzip the covers and replace the sprung inners for the foam.
Just one word of caution if you are thinking of doing the same, GB Foam (together with most other foam suppliers websites) recommend having a dacron wrap top and bottom together with a stockinette cover. We found that having the dacron top and bottom was too bulky so we removed the bottom dacron for a better fit. Hope this helps anyone contemplating the issue.
Now all we need to to be able to get out touring.

We did the same,[different Co] using Reflex foam, made all the difference in the world for comfort, those spring ones were awful.
Dave

Well done. Modern quality foam is streets ahead of the basic antiquated spring frames in an Eriba.

Stewart

Now, we prefer the sprung cushions in our Troll, they are so much more comfy than the foam ones in our younger Lunar Lexon. I do like a firm bed

My uncle used to work for GB foam in High Wycombe

We decided to have the springs removed and replaced with foam. Best thing we did when we had the seat covers replaced, so much more comfortable

I prefer spring for sleeping with a reflex foam topper