Just did this yesterday.
Took 5 mins.
Pay $50 + 7 taka at the bank (so $51 and get 70 taka change from the bank man)
Then go to the man at the desk with the ledger with the bank receipt
Then go to the front of the VOA /investors/diplomats line
Easy. There was also a sign at the bank that said rate can be paid by 43 Euros.