I got an offer to work as a contractor (W2) at a major social network company in the SF Bay Area. The person from the 3rd party agency (the one I will be officially getting my paychecks from) has been dealing with me with extreme urgency, demanding all necessary documents and requesting me to sign all the paperwork as soon as possible, so I could start on August 20 (a Monday).
That was all ok for me, so I just submitted everything that was requested and resigned at my current (former) employee with appropriate notice. Since I have a tight budget and don't want to go too long without getting a paycheck, I set my final date to the middle of the week before Aug 20.
Up until Friday 4pm everything was fine and on track for my Aug 20 start date. That's when I receive a phone call from this 3rd party agency saying that it would have to be delayed by a whole week (to Aug 27th) and I wouldn't get paid at all for the week of the 20th. At first the person said it was because my background check was delayed, and then she changed the story and said it was because other contractors would start on the 27th and it would be easier to have everyone onboard together.
Regardless of the reason, I feel that since I had confirmation on the start date and quit my previous, stable job, that's a really unfair treatment. It has bothered me a lot over the last couple of days, and I really want to pursue a resolution on that (I feel like getting paid in full for that initial week would be pretty reasonable). But at the same time, I don't want to be too aggressive, since this is a new job at a company I don't know anyone yet.
What do you think is the best course of action here?