I'm not aware of any software which will read braille and covert it into text. I think your best bet would be to contact the RNIB's library.
http://www.rniblibrary.com/iguana/www.main.cls?surl=a1
They have books in braille and will send them out to braille readers. They are likely to have braille readers amongst their staff, and if a sample was sent to them they might be able to check it for you or send it to someone who could.
Also, do you know the name of the software package they used to convert it? Usually these systems just convert a word document into braille so if the software is decent it should, theoretically, be an accurate conversion. However, the accuracy sometimes depends on the way the word document is laid out. I've used these systems before and they cope well with blocks of text like what I'm typing. They don't cope so well if there are tables, as in braille you cannot get as many characters across a line as you could in text. So tables are often broken up.
Another thing to be aware of is that there are several types of braille you could be asked for. The good news is that an up to date conversion programme should be able to easily work between them.
Grade 1 English braille is the most basic and is essentially the letters of the alphabet plus some punctuation and numbers.
Grade 2 English braille is like shorthand and uses lots of abbreviations and contractions to shorten words.
A few years ago things got more complicated as the English speaking nations got together and developed UEB - or Unified English Braille code. They made a few changes which mostly involved punctuation. But, no need to panic as text to braille converters should be able to easily cope with the above..
