I had to get a couple of Sigmas rechipped when I bought my EOS 10D and the service from Sigma was excellent. They had it done very quickly and returned the lenses within a week. So it should not be too onerous a task to get yours sorted.
(The fact that the Royal Mail then delivered them to the wrong address and couldn't get them back for some reason was not Sigma's fault, I saw the signed and dated delivery slip from the Royal Mail. Sigma sent me two new replacement lenses without argument).