Failed my Test

Hi, I'm a noob here and have a couple of questions. First off I have read a lot of the threads but so many are quite old and I need some up-to-date info.

About me: I am a skinny, 5ft 11 and about 140 lbs but not very active. I shared about 4 doobs over a weekend 10 days before the test.

I had my urine test on 12/30 for a new job (well the company wanted to re-hire me after being laid off 18 mths ago). I bought some Test'in 90 Minute Tea Cleanse from another site. I took multivitamins and water the day before as per the instructions and tested myself - I failed. I brewed up the tea using a gallon of water and drank it before going for my test peeing a few times then tested myself again. A very, very feint 2nd red line was showing. I thought I would be ok and went and did the test at LabCorp. It took them until today (01/10) to get the result which I failed.

I was devastated and got back with my would-be boss telling him I really would like to get another test as I couldn't believe the result. I told him I was using ibruprofen for a tootache and zantac for heart burn/acid reflux. He is contacting HR to see if they will allow me to re-test but as its a big company I suspect the HR dept will not allow me.

OK, thats the background. Here's my questions.

With LabTech (or similar companies) for a re-test would they be present while I'm providing the sample?
Would you suggest dilution or substitution?
Are your stickied threads still relevant in 2011 or have these testing companies updated their methods?

I was never told what I failed on (but it must be THC as that's all I take) or what the specific amounts were.

Thanks for any help.