Did you pay the extra $60 for 3G? 3G is optional and you have to pay extra for that model.
 You can try newer firmware to see if that fixes microphone. Tablet maker calls it M728 & not T9.
Use Google Translate if you do not speak Chinese.
Cheers for all the comments. Yes, as far as I'm aware, I did pay extra for the 3g version as it came to about £180 for the tablet + delivery, and according to Merimob's it's 120 for the regular version. So I managed to get the sim in to sit, but it's currently not connecting to any 3g. To be fair, MM'iles said they would email the manufacturer and see what the issue is with both and see if it can be fixed.
According to Merimobiles, there will also be a better 2.3 firmware released mid September, so I'll hold out for that one before upgrading it. All in all, I LOVE this tablet - just need the mic and the 3g and I'll be one seriously happy customer. The main benefit for me is that I actually work in China at the mo, so if I need to send it back, it's not that much of a hassle. I'm just glad I don't live in Shenzhen (where pretty much all these tablets are made) or else I'd be seriosuly broke.