Timber floor problem - advice needed!

Hi guys, I am building a duplex that is almost finishing, one of the units has polished bamboo floor, but the edges have expanded and the board have curved a little, not too bad but definitely not flat (floor laid about 6 month ago).
Spoken to the floor guy, he said it was due to moisture in the air and no one lived in the premises and then sunlight shined directly onto the floor boards, he offered to sand the whole thing and re-stain it, and saying that floor boards are only change to an extent, after sanding it will not change shape any more.
The problem is the purchasers will not agree, they want the whole thing to be dug up and replaced with new boards. (house already sold, but not settled yet)
I spoke to department of fair trading to see what the standards are and what rectification is acceptable, but it seems no such standard exist.
And the floor guy is saying that sanding it and re-oil it will be "made good", any one had similar experiences? What can I do? Is there a set of standards or regulations so I can sort it out?

This is an interesting one Hector, as it seems it has been properly diagnosed, but both solutions may be acceptable too.

I've seen this happen with a lot of new homes, where the timber is delivered but doesn't have time to acclimatise before being laid, and/or where reverse cycle A/C is installed and the moisture content changes.

In some instances when I was a builder, we replaced the whole floor. In others, we have sanded and re-coated the floor. There are a few things to consider as to which might be most suitable.

First, if you have bamboo and it was pre-finished, then you will want to check with the timber supplier (not the installer) as to whether sanding and re-coating is suitable.

The other is to check if the timber has cupped at all, meaning if it has expanded, the board might now be concave width wise. If that cupping is too significant, you're losing some contact with the ground along the edge of the timber. So sanding the top side might make the top flat, but parts of the board are losing contact with the ground. This can create movement later after normal wear and tear from foot traffic and the boards may come loose at the joints.

The best solution will always be to replace the floor entirely. If that happens, you want to get the timber delivered, and store it inside the house for a few weeks before it gets re-laid. This allows the timber to acclimatise.

I'd also recommend you contact the Timber Advisory Centre http://www.timber.asn.au/tac and ask them their advice. They're experts with the different types of timber and their properties, and may give you a more definitive answer than I can.