Irritating PoA mistake

[Amanar]

No: HPFGUIDX 95844

PoA chapter four - "The Leaky Cauldron". British edition p. 44-45:

"As harry entered flourish and blotts, the MANAGER came hurrying 
towards him..."

"A look of enormous relief spread over the MANAGER's face"

'Ah, starting divination, are you?' said the MANAGER..."

"'Here you are,' said the MANAGER, who had climbed a set of steps to 
take down a thick, black-bound book. 'Unfogging the Future. Very 
gook guide to all your basic fortune-telling methods - palmistry, 
crystal balls, bird entrails...'
But Harry wasn't listening. His eyes had fallen on another book, 
which was among a display on a small table: Death Omens: What to Do 
When You Know the Worst Is Coming.
'Oh, I wouldn't read that if I were you,' said the ASSISTANT 
lightly..."

"The ASSISTANT pressed Unfogging the Future into Harry's hands.
'Anything else?' he said.

When did the manager turn into an assistant? Last time I checked, 
the two aren't synonymous. But then again, that may have been an 
extremely long time ;)

Amanar, who hates-hates-hates inconsistencies. 
(A perfectionist, what can I say?)