architectural export not working from Unreal

Hi, I hope you can help.

We’re an architectural CG illustration company that’s recently started using Unreal as a tool for showing our clients their project areas. We’ve created the model in 3D Max/Vray and then completed an Unreal workable file from that. We’re having terrible trouble exporting from Unreal, we’re getting different error messages each time, or sometimes the character is floating, sometimes not. Sometimes we’re simply told the file could not complete the export. We’ve followed the official documentation exhaustively along with whatever we can find online.

So my question is firstly, is there paid support that can help us identify where the problem lies, and secondly, can the paid support offer us a bullet proof working procedure that we need to follow every time we export. This extremely important to us as using Unreal will hugely affect the quality of the services we can offer our clients, but more importantly, we’ve turned down projects as we can’t fulfil the clients needs when it comes to what Unreal can offer.
Any help would be fantastic, thanks.