I'm afraid I agree with Niki mate. 4-5 threads is not sufficient, and titanium being way harder than aluminium, they will just pull right out. Were the threads in the chain cover in good shape before you took it to R Tech? Do you suspect they over tightened them and they then pulled out under the load or something? These things are always your word against their's unfortunately.
The thing with pressure....think of it as resistance. Oil pumps, turbos, fuel pumps, meth pumps etc...... none of them create pressure. They create flow. Pressure is the resistance to flow, and it's that 'resistance' which brings Newton's third law into the equation, which is: "For every action, there is an equal and opposite reaction". So when Niki commands and extra 55 bar of pressure from the pump (that's 800psi of additional resistance!!), that is a LOT of additional force on the bolts.
Also remember that VW designed the pump mounting hardware to sustain 110 bar, max. When you push things beyond their design brief, you're on borrowed time.
What I don't agree with, if it's true, is how you were treated as a customer. I don't know the guy, but he has a good reputation and I can't imagine him swearing at you down the phone unless he was provoked? Professional suicide!
Anyway, get yourself a new chain cover and move on mate. Bin that silly sensor cover, I hate those stupid, ugly, pointless things 
why would they pull right out if the when they were secured by myself and I'm confident in doing so?.
Imho there is nothing wrong with fitting titanium bolts into aluminium as long as you hand tighten them up making sure you don't cross thread as same with oem bolts, you can still strip the thread either way!.
The threads were perfectly fine before this happened as I always push the pump home then hand tighten before using a spanner and as you will all know I had issue with lag or boost a while back so had to remove the pump a couple of times to trial and error and finally found the used pump being the cause so swapped the VIS internals over to my original pump and power was back up again.
I also understand the physics of it all but imo there was nothing wrong with the way I fitted this on BUT let's leave it there as I don't want it to escalate as Niki mapped the car to an awesome spec and don't wish for any name calling or pointing fingers anymore.
Also, No I didn't provoke him as all I said over the phone was the threads are stripped and two bolts have popped out and in he's own words he said on Facebook were "I spat my dummy out" which he certainly did and that was more upsetting than what happened to my car
as to me it was an easy fix and not a knackered cam!! Vis internals
it was Niki who posted up on Facebook and people making judgements and comments about the owner aka me.
Oh yeah I ent getting rid of the plate as it gives definition to the engine when the bonnet is open
