Haven't read through the whole thread but I have dealt with lice exactly ONCE while it has gone round and round in my kids' classrooms so I consider mine a sucess story.
DD6 had lice (none of the rest of the 6 of us got it and I had slept on the same pillow as her 4 nights in a row before finding the lice!)
Anyhoo, treated DD6 with LiceMD (it is non toxic and worked VERY WELL) as written on package except that instead of combing out nits I CUT off each hair that had a nit on it and sealed them all in a ziplock bag before throwing it out.
I treated everyone else in the family with RID with a quick comb through (after initially not seeing aNy nits on heads).
THEN I vaccuummed the crud out of our house, EVERYTHING got vaccuumed- floor to ceiling and then some. Anything furry or cloth was placed in trash bags in the garage for 72 hours (couch cushions, stuffed animals & dolls, pillows, etc).
All hair ornaments, brushes, combs were tossed out. From that point on everyone had their own assigned hair stuff and ALL of it was kept in seperate ziplock bags in the freezer (this was over 4 months ago and the brushes are still in there- brush your hair in the morning and put it back in the freezer!)
DD6 was only allowed to sit on the leather chair or kitchen chairs for a month NO COUCH, her bedding was collected and washed every morning immediately after she woke up and it all staying in the dryer until just before bedtime. I also vaccummed her matress and all around it every morning after stripping it (did this for 2 weeks). I'd make her bed, she'd go to sleep and as soon as she woke up I'd strip the bed of everything and throw it back into the dryer (once a week doing a full washing & drying).
After all that initial stuff I checked her hair every night for 2 weeks and cut out any nits then treated her hair again on day 7, & day 14 with LiceMD. I did find additional nits, but never any live lice after the first day (she had 25 live lice and over 200 nits that 1st treatment- she thought it was fun to count them all?!)
I keep her hair in braids when she is going to school (or scouts or anywhere that other kids were at) and every Sunday we STILL do a critter check on all the kids just in case.
So while I was doing all of this obsessive critter hunting our neighbors have had it 4 times each kid, GS coleader's kids (who gave it to my kid) has had it 3 times and most of the kids' school has had it at least once.
The common theme is that they treat the kids' heads and don't clean the environment and/or they don't follow up to kill the newly hatched lice. I don't care what anyone says ,there is no meds out there that will kill the nits- you have to physically remove them AND treat the hatched/hatching nits for at least 14 days after the original infestation to get rid of it entirely. The nits have a lifecycle of 7-10 days so if you treat 2 more times at 7 day intervals, after the initial infestation you should be able to kill everything.
I'm sorry you had to pay so much to have someone do the removal for you. It was time consuming but quite honestly I think they took advantage of you in a scary situation.