In the USA, I used safetyrestore.com. the webbing was color matched to the seats and they matched factory stitching and had the original mfr tags put back in. Took about 3 days and was about $100 us a belt.
I used FDTS as the other company took 10 days to respond to my enquiry. FDTS were simply first class - they replaced the webbing on my inertia belts and returned them within a couple of business days. Highly recommended - many thanks for the tip!
Cheers, Philip 2019 Morgan Plus 4 BRG Mercedes SL400 (prev)