You should be able to get a replacement liner from Mercedes. Alternative is to look at airconditioning/insulation companies for alternatives. I used a product called Thermoflex bought locally (Johannesburg, South Africa) when I rebuilt a 1966 Jeep Wagoneer. Getting the old stuff and old glue off the bonnet is a pain, needing lots of elbow grease. Easiest to remove bonnet from car - with help. Just mark your hinge attacthment points before removal.
Thanks for that, i got the liner from MB who told me to go to a store and buy a spray on glue, can you recommend a brand? My local car parts store were reluctant to sell me any for fear of the "high temp in the engine compartment could cause the glue to ignite"