Too right - DONT accept.
You can easily prove that most manufacturers charge more for the Dolby version of the same Nicam TV.
On the subject of Dolby Digital 5.1 on the cheap checkout the Novatech 5.1 speaker setup for £99 inc VAT at
http://www2.novatech.co.uk/novatech/...code=NOV-HT510'
I replaced my old 4.1 Dolby Prologic amp and speaker setup (this was a cheap Sony Amp, Wharfdale centre and 4 Aristons) with the Novatech 5.1 and it definitely sounds better. I have only had it for 2 days yet but the main battle scene at the start of Gladiator sounded so much better. You could hear the bow, arrows, catapults, firebombs etc so much more clearly than my old 4.1 setup. Even the missus admitted it sounded better - she normally thinks all this is a waste of time.
Obviously, you need a DVD player with 5.1 decoder built in - as you say you have.
Alternatively, if they are prepared to give a Nicam TV plus say cash compensation then you may want to consider the VideoLogic DigiTheatre
http://www.videologic.co.uk - the one with the Dolby Prologic and Digital decoder plus 5.1 speakers for £200 from
www.qed-uk.com (check under Audio/Home Cinema).
It has had some great reviews from both AV and PC magazines.
I nearly bought the Videologic but a recent Car upgrade and TV upgrade meant I had to compromise with the Novatechs. Dont watch that much normal TV anyway.