Flight Simulator X and the Saga of Acceleration

I feel like hitting something! After a week of trying to install Acceleration over Flight Simulator X Deluxe, FSX has become corrupted and won't start! This means I will have to uninstall the lot, and start from scratch, while making sure it really is from scratch, as remnants of the installation will no doubt linger in the Windows Registry and various other nooks and cranys of Windows. I'm not all that confident about this, so I checked the Microsoft Support website, which cheerfully informed that I would have to pay £46.00 for support. I cancelled. I payed £22.99 for FSX at amazon.co.uk, and I don't see why I should pay double to make up for the incompetence on the part of Microsoft. They made a brilliant product when it runs properly, but when it fails, it creates a tormenting nightmare for all simmers.

Help.