2 metal framed folding sun loungers (Epworth DN9)

This is an upcycle project as the elastic bungee cords need replacing on one of the sunbeds for sure. The cords on the other are starting to fray but not to the same extent. The elastic on the headrests is also loose, as you can see in the photo, one has frayed completely. I attach the link for where I purchased them from.
I also attach a link for where you may be able to purchase replacement elastic bungee cords from.
They are very comfortable to lay on and the only reason I am not effecting repair is due to the fact I have bought new garden chairs.
They retail at £ 80 currently on the Argos website but could be repaired for much less. Ive had them at least 2 years and used them a lot.
http://www.argos.co.uk/Metal Sun Loungers - Yellow272/2489
https://www.ebay.co.uk/splashui/challenge?ap=1&appName=orch&ru=https%3A%2F%...