It seems the original poster has not returned here since a few days after posting the problem some 8 months ago.
Of course opinions vary, and I would certainly go along along with your sound advice Phil to consult a trusted auto electrician if checking and changing the simple components do not solve the problem. Where my opinion would differ in this particular case is that within the bounds of probability, it would be unlikely that a total of 3 batteries ( 2 new) would be unserviceable - particularly when they have been tested by three separate battery-selling outlets.
It would have been interesting to know exactly what the problem was caused by.
Kind regards,
Gareth.