It sounds like your yeast is old and weak. It has fermented some (the brown sugar would have boosted your O.G. into the low 1.040's and now it's 1.029), plus you saw a little foam on top. At 70°F for a couple of days, it should have gone crazy if the yeast had been fresh. I would still recommend you add a fresh pack of Cooper's or Munton's if you have a LHBS nearby. Add the yeast and bring the LBK into a little warmer temperature until it kicks off. The fresh yeast may, or may not, kick in and finish off the fermentation, but it cannot hurt.
Scott Birdwell
DeFalco's Home Wine & Beer Supplies
www.defalcos.com
+1
It's a little difficult to tell exactly how much the brown sugar added. Measuring ingredients can be a bit problematic because it's less exact than weighing. Depending on how tightly packed the brown sugar was, you may have even gotten the OG up to around 1.052. Using the rul of thumb of 75% attenuation, you'd expect to get to about 1.013. But since the brown sugar is almost completely fermentable, I think you could get even lower.
As deflaco points out, you've had some signs of fermentation (the foam on the top is the krausen to which I alluded earlier) and your gravity dropped some, but not nearly enough.
I also agree that with healthy yeast, it should have really gone crazy.
Since the WCPA is part of the old line and Cooper's acquired Mr Beer in April of last year, you're using some old yeast. The yeast packets that shipped with the old kits were small to begin with (I used to save them up and use 3 at a time). Since the yeast is also old, you're looking at a serious underpitching situation.
The directions that came with these kits said to stir vigorously, but they didn't really explain why, so many people didn't understand that the reason for the stirring was to introduce enough air for the yeast to be able to produce unsaturated fatty acids and sterols during the reproductive phase. If you stirred to mix the ingredients, you likely didn't get enough air introduced. So you started with too little yeast, then didn't give the yeast what it needed to reproduce in a healthy manner. It's entirely possible that the yeast you ended up with won't be able to fully attenuate.
If you can get some yeast from the LHBS, I'd do that. If you can't, since you've seen some signs of fermentation, I'd wait a week before resorting to using bread yeast, but if it doesn't drop any more, bread yeast is technically the same species as ale yeast, but they're different strains and are bred to favor different characteristics, so a yeast bred to be used for brewing is much better. I've used bread yeast before just as an experiment and it works, but it would never be my first choice.
As an aside, as a rule of thumb, you should try to keep adjuncts (simple sugars, like table sugar, honey, syrup, brown sugar, Booster, etc) to less than 1/3 of the total fermentables in a batch. The WCPA + Booster already breaks that rule. With the addition of the brown sugar, you've almost completely flipped the ratio, and are getting almost 60% of the alcohol from adjuncts. You'll probably want to let this condition in the bottle for at least 2-3 months before drinking any.