Sullen Silence?

Have I offended Barclays?
My rejection of Malone's findings has been met with a wall of silence.
How can I extract a confirmation that Barclays has received my letter?
On the 4th October I emailed a letter with an attachment giving detailed responses to the points Ian Malone had presented. There was no response. No automated system generated message to offer confidence that the email address Malone had provided was the correct one. No postmaster message to say that the address did not exist.

Deja vu. This communication black hole was where Paul's January 2016 request to transfer his pension allegedly ended up. 

Barclays alleged they knew nothing about Paul's email, and now they are staying silent on mine. 

This failure to acknowledge leaves Barclays with total deniability. 

Now I'm in a similar situation, but with more information than Paul ever had what can I do? 

I sent Colin White a physical postcard via Touchnote so that there will be an audit trail, with what I consider was a polite invitation to communicate;

No response.

Today I had a look at the Barclays UK  Facebook page and it does appear to be serviced and so I placed an enquiry there too.

So, for today that's about all I can think of doing. And as Paul would say, "We'll see."

Unless they are all suffering from an extreme case of institutional communication apprehension I can't see why sending a simple 'read receipt' should be too demanding.