Found a relevant website www.frostfighter.com
that offers repair kits. They also offer a repair facility lookup function. I found a shop about 50 miles from here.
Once I have done some troubleshooting I'll decide whether to take it to the shop, or DIY. I hope to keep you posted
'96 E300D 58k mi (wife's daily ride)
'95 Audi 90 118k mi
'92 GMC Suburban 138k mi
'85 300SD 230k mi (my daily ride)