the perils of ebay bargains

well, slowly I am getting there with this whole pictures thing in japanese. (working on mum's japanese laptop. very difficult when you can only read about 50 characters out of about a million and I really have no idea of changing language settings on blogger)
The above pic is of a cross-over cardigan in cashmere i ebayed. Sadly, I am half way up the second front side and have discovered that the yarn has gone from a 4 ply to a 3 ply.
It looks like I will have to un-ply yarn to get to the end of the side and the back and sleeves will be knitted in 3 ply and on smaller needles as I don't think I will have the patience of untwisting yarn any longer. It is also annoying because it means I am going to have to recalculate the pattern to compensate, which is annoying as I have to actually get the calculator out and waste more yarn on swatching. I also don't know if the yardage the ebay people gave me will be enough if I am knitting at a tighter guage.... well I suppose there is only one way to find out and that's by knitting it, and I can always order some more in another colour and dye the whole thing black (I wanted a greyscale coloured cardigan so going black is no big issue... just another bulk of money added to the total cost. ho hum)... and lets hope they give it to me in a three ply or else I can't finish off any sleeves I've already started, or I'll end up with a lop-sided cardigan... or something terrible.
I am just annoyed it's taken me so long to notice the transition in the yarn cones... otherwise I would have asked for a refund/exchange.
I may use the seller again but I definitely will be staying clear of the "twisted by us" yarn.