pygmy date palm (Phoenix roebelenii) dying - help?

[PeoniesforMissAnnersley]

I have a formerly lush and lovely Phoenix Roebelenii which has over the past few weeks wilted and become greyish-brown and crispy. There's no yellowing or orange spots and I can't see any parasites on it.
It isn't even a proper brown, just looks very dry and wilted, although we have watered it (honest!)
The centre bit still looks alive and upright but 80-90% of the fronds are not happy at all.
Any advice much appreciated.