In that case, it's an annoyance but nothing to worry about.
How to proceed - you either wait for the belt or say forget it. I imagine you'd like it so probably worth waiting for. And if you only order custom things from makers who aren't flaky, then you're limited to a very short list.
Did yours eventually arrived? I ordered 2 MTO back in Sept 12. They made them in the wrong size and sent one in a totally wrong color and buckle. Has been promised with the right replacement since Jan 13. Moving forward to 23 Mar 2013, still nothing, just frustration. Unfortunately for me, I paid in full.