replacement roller blinds 2002 Boxer Symbol

Any suggestion how we could find replacement for our sliding door roller blind as well as the main roof light roller blind which are fraying? Our dear "Ernie" is starting to show his age, cracking up a bit here and there.  We even had to come back from Swanage last week on the back of a flatbed truck because of a Brocken clutch pedal 

Hi. Sorry to hear Ernie is suffering a little. Our Bessie is showing her age too. Have you looked for local caravan, Campervan breakers yards? They can be a good source of parts for the ‘older van’

Thank you both Robbit M and Roger Black for your useful suggestions.  We shall explore both...

It looks like we have identified 2 types of Seitz cassette roller blinds from Leisureshopdirect which could be compatible with our van.   We just have to wait until Ernie is back from the garage to compare the windows with the company's diagrams.  So, progress have been made.