I was recently let go. payment in lieu of notice?

My employer let me go on a Wednesday. There was a general layoff for other employees the friday after but I was let go early due to confidential issues as I worked in HR. I was told I would receive severance and be paid through the end of the month. Howwver when I got my final paycheck I only got paid 25 hours of regular paid (till the date i was let go) and then NOtice pay of 7 days and termination vacation. While others being laid off would be let go on the 15th of the month and get 2 weeks payment in lieu of notice till the end of the month and then severance. I was employed for 2.5 years with the company. My question is should i rceived the full 2 weeks pay in lieu of notice? also, what taxes are supposed to be taken out for my last paycheck and for the sevrance paycheck. Thank you