Thanks for the replies guys.
Honestly I wasn't aware of this issue before, it just happened that I never came across any information describing this particular issue with the old 5D's.
Any way luckily I had a third body at home which happen to be Canon 5D MKII, so as soon as the second mirror fall, at this time I still was at the bride place covering the preparation, I asked the bride brother to call me a taxi and I went all the way back home to pick up my third body. Good thing was that there wasn't much traffic that same day, so after all I missed only the arrival at the church.
I didn't have problem fixing the cameras, in fact yesterday I picked them up from the office of Fixation.co.uk.
I'm just still in some sort of shock as it is hard to believe that such thing can happen at the same day.
As for tetragramaton it is a very long story