dude it sounds like your builder is a corner cutter, what yu need to do is call him up, try to get him to pay for some of the bill, and believe me its gunna be a big one, in the northwest an average drive way to repair it between 4 and 6 thousand bucks, to jack hammer it out add fill dirt oh, and the most important part WATER SETTLE!!!!!! AND COMPACT then yu gota do a COMPACTION TEST!!! if yu want to be sure it wont happen again.. the good news to all of this is that yu only have to take out the panel where the expansion joint starts the bad news is that your corner cutting contractor could have layed down a 20 foot panelwithout an expantion joint (OUCH! now that hurts!) bottem line here my friend your contractor should take up another trade he obviously doesnt know the one he is in. i know a guy that thinking of taking up underwater basketweaving maybe hes looking for a friend.