Assuming the equipment was not defective, was your return within the 30 day period for returning equipment under the "satisfaction guarantee" policy from X10? If not, you are at their mercy. Even if an X10 rep said "yup, your refund is in the pipe" I suspect sometimes customer service telephone reps just say whatever necessary to get you off the phone and move on to the next caller. And that isn't just an X10 rep.
Before spending money on an attorney, I would go back X10 one more time and explain you are writing the Washington State Attorney General about their empty commitments. Speak to a supervisor and get names. Then after a couple of days with no action I would go to the credit card company. If you have any documentation from X10 indicating they received your return goods in good order, when they received it, etc. I would forward that information to the CC company also and see if they will do something. If all your communications was over phone, do you have records of who you talked to, with dates and times, if so forward that to the CC company. The CC company can do a charge back to X10, but considering the time passage you will probably need some verification for the CC Company that the problem is at X10's end.
If that doesn't work then maybe a letter for your attorney will get X10 to do something, but I think X10 HQ is probably chaotic.
Good luck.