Regarless of product name a light that legitimittly produces uvB is in immediate order. Two things concerned me with what you posted.
One, the fact that they gave you was at best "crappy" information in regards to proper husbandry and diet probably means that they where in fact using it. If they are good knowledgable sells people they will go at great lenghts to disclose proper information in an attempt to jack up the sells. These flourescent bulbs have to be replaced every six months, they require some sort of ballist, and that adds up to a repeat customer $$$.
Second, if this Jackson was being held at this pet store for a substianal amount of time he is probabely in poor health. The two symptoms you gave where lethargic behavior and poor appetiate. These could be symptoms of many different health problems. The one that immediatly pops into my head is MBD given the information that was provided.
I would at this point check the Jackson over very well. You will be looking for several things: swelling at the joints, bumps at on any part of the skeleton, broken toes, curving of the long bones, jaw shutting flush (underbite is normal, we are talking horizontally), "S" ing of the spine, a tail that does not roll up completly (or flacid), tremors (noticable most at the feet), inability to properly support weight (most notably in the rear section, "dragging his butt" so to speak), favoring feet when standing, and some report noticably ruinier stool.
I have heard that in Jacksons with MBD that the ends of the horns become noticably opauce but this is not a reilable source. Just curious if anyone else had heard of that.
I would do this check in conjuction with some further research in this area. I would think at this point you have multiple options. If he is showing more substainal signs then the ones you listed perhaps you could return him for a refund. If they will not refund your money a trip to the vet is in order. If he is not showing more substainal sign I would keep these thoughts in your mind. The two things that cause MBD are improper husbandry, improper diet or a combination of the two. Researching of proper husbandry and diet can start on this forum. There are multiple people who own or have owned Jackson myself included. The reason I said keep MBD in mind is simple. Beginning cases of this can be cured with no trips to the vet or adverse effects on the chameleons lifestyle. Cases that are allowed to advance can get ugly.
Husbandry is not just numbers but rather providing them with an enviroment that encourages natural behaviors. Just feeding them food is not enough you have to feed the feeders properly and adopt some sort of supplement regiment. A jacksons is a demanding chameleon to start out with but it can be done. When you do these things good a chameleon can be a very rewarding pet to own.