Were there unforeseen matters? Did the transaction take time above and beyond the scope of what was envisaged? Or was it just a run of the mill purchase?
"At no time has he mentioned......" is annoying, but may well indicate bad communication skills rather than overcharging. So forget about that issue and concentrate on the real issue - i.e. was there extra work?.
If your solicitor is trying to take advantage of you, say so to him and make clear that you intend to complain.
If, on the other hand, there genuinely was indeed extra work involved you might chide him for not specifically bringing this to your attention weeks\months ago instead of right now; but I would go ahead and pay ( and haggle)