Go on then. I'd be happy to speak to them, but an email address would be even better.
As soon as you mix tyres, you alter the balance of the car. Having two different different grip levels is bad enough, but three? And mixing across an axle? Sorry, but there's no way any manufacturer is going to recommend that last one in particular. It doesn't matter if it's a 206 or a Veyron, 70mph is still 70mph and accidents happen, and I certainly would want to give myself every chance of sorting the car out should an incident occur. Someone in your line of work really should know this, it's very basic stuff.