Like most lay people I was looking for a black & white answer but now realise that this is not possible.
I entered my original question on Answerbank after considerable research on the net.
However the available information is either so simplistic as to be useless or so detailed as to be incomprehensible (to me). Your answer has enabled me to accept my 'diagnostic' limitations.
Unfortunately my wife, 'client' and I are still at the the end of our respective tethers.
The client had his oesophagus removed and replaced with a length of colon. The 'new' oesophagus/stomach interface is not working and he is still experiencing acid reflux and also cannot speak properly because of damage to one of his voice box nerves with subsequently disturbed sleep following food/reflux? entering his lungs and causing choking.
It is over four months since he saw the surgeon who promised a revision.
Please ignore this diatribe, no response expected, but I had to tell someone.