So as of 19 August the amp was all but ready, but more weeks have gone by with no news.
Well suddenly it looks like we're into a slightly different problem - see part 39.
It is now nearly a month since your last email and my subsequent reply has not been acknowledged (both below).
I feel I have been very patient considering that you have had the amp since the end of April. I do not understand what the current delay is in view of your previous assurance that it was fully tested by 19 August.
I would appreciate some action to finish any outstanding work and get it back to me.