I have to say, the folks in the Perth branch have always been absolutely lovely whenever I've had to deal with them - and this despite them having to deal with a human wave of arseholes, day in and day out, as well as a job that seems rather complex.
The big lines seem less about "poor customer service", and more that you do everything through the post office nowadays - some of it quite ferociously bureaucratic. All it takes is one slightly deaf old lady needing to renew her passport, or someone with ropey English wanting to renew their car tax, and BAM, that's a member of staff tied up for fifteen minutes.
Now the Dunkeld Road post office, they can get tae. Bunch of evil natured old dragons.