EC120 seat belts
I had to renew mine a couple of years ago. I was quoted a silly price by EC.
The cheapest way to do this is:
Rear Belts: contact the manufacturer Amsafe at their Heathrow office. They can reweb the belts for about £25 per belt (so a rear belt is 3 x £25 + the retraction overhaul) This take a few weeks, so if you are in a rush pay the AOG fee as well.
Front Belts: these are made by Pacific Scientific. Their Heathrow office charges a silly price, so I sent mine to their Miami office - takes about a week. If you don't want to be grounded, send the front belts one set at a time.