Review and raise up to £2.00
The website looks ok, and it certainly generates quotes.
2 - When they do respond, the links within their system generated emails don't actually work, therefore, you can't access or read anything that they may or may not be sending you.
3 - The breakers don't care if they get something wrong. You'd need to force the issue via a claim from your card issuer or PayPal depending on how you've paid for it. I'd use PayPal if I were you, as their dispute resolution process is quicker and easier to use.
4 - eBay tend to be cheaper, with much better support (not that it's great) and an easier resolution process if you get a problem. Automend (the Registrant of the Partsgateway.co.uk domain) have no direct contact details registered online, therefore, it's not possible to contact them in any way other than snailmail which is next to useless.
Their registered details are:
Unit 12, The Sidings
That's it. Good luck if you get a problem...