TV cake-not as easy as it looks!

Well, it was bound to happen, I had a cake tragedy. I am trying to look at it as a lesson but I'm so tore up that I did not deliver a product that wasn't what I promised. Here is the set up. A mother of the groom (MOG for short) called me with 10 days notice because her other baker decided she could not handle the cake they wanted. The MOG met us at the Dalton Bridal show in January. They didn't use us because they were told, not by us but lots of others, that no baker would make the bridal cake they wanted because it had live goldfish in between the tiers. Anyway, the request was for a 3-D flat screen TV cake with ESPN on the screen and any prop items we had time to make. We made a box out of 1" x 4" wood and 1/4" hard board in the back. We drilled a hold in the bottom and a piece of PVC with threads went all the way up. My brother made me a great stand that was heavy with a metal thing in the middle for the threaded rod to screw into it. I just saw them do this sort of thing on "Amazing Wedding Cakes". The cake girls made a great box of sweet tarts. Those shows make it look SO FREAKING EASY and it's not. We spent hours on this cake, 7 decorating. We set it up and it looked great. THEN the fondant screen starting sliding. It tore at a weak point that should not have been, I don't understand why it did what it did. We sat there for 50 minutes and watched it slide and total of about 1/3". I used black royal icing to caulk the boo boo, it looked fine. We left, went shopping at Wal-Mart and the ladies at Trevitt Hall called and told us it was buckling. We went back and it was about 15 minutes to show time. The screen had slipped another 1/4" inch. I did the same caulking job and it was still OK. 85% of people would not have noticed it. I had to leave and hope for the best. About 11:30pm the venue called and told me that as someone was walking by, the cake PVC rod broke and fell. Luckily the person caught it and nothing hit the floor or anything. They laid the screen down on the table and cut it as a sheet cake. Everyone got cake and it didn't break until after everyone sat down for dinner. I guess that's the good news? I don't know how upset the MOG is, but my heart is broken. What I learned....I should have insisted on a pound cake. I should have used a metal threaded rod (I don't know for sure that the PVC snapped until I pick up the stand). I should have stacked the cake in small layers, as opposed to the big sheets of cake that filled up the box. I should have put it vertical the day before decorating it so it could settle all that it wanted before I put the fondant on. I think I'm going to do the cake again and see how it goes with all my newly gained knowledge. Tomorrow is another day.