Going Crazy: screen printing imperfections?

I am new to the forum and am hooked! I have been in the process of starting a new apparel (mostly tshirts) line for over 1 year. My business is still in my house. My product is very cute and very novel (currently geared towards kids), but somewhat complex. My problem is my product has a screen printed logo (6 colors) as well as an embroidered patch applique. Unfortunately in the two last sample batch runs (approx 70 pieces each), atleast 70% have imperfections from the printers end. Borders around applique are inconsistent, appliques not placed on straight, position of logo too low, etc. My printers seem to have a very successful operation and some major clients. I have been affiliated with my printers for a while and feel I am very invested with them. To walk away at this point would probably set me back 2-3months of launching not to mention additional $$$. Here's my question, my designs have a .25" glitter border around a 3.5"X1.0" patch. Most of the discrepancies on the finished product have been in the uniformity of the border (ie: the right side of the border may be .25" and the left is .15"). Even though these measurement differences sound negligible, they make a significant difference for my product. My printer has suggested that that the shirt contents makes a difference on how the print will come out (ie: ribbed vs. cotton). However, some of my ribbed tanks have come out perfect and some look awful. Since this is my first expereince in the tshirt business, and I am not familiar with the in's and out's workings of a printing shop, I can not understand what exactly is going on. I have supplied my printer with EXACT artwork and call out sheets (at the cost of hiring a graphic designer). I am just so frustrated and don't know what to do. Also, my printer has invoiced me for the samples completed and I am not sure how to handle this since a majority of the samples are not saleable or useable. Any suggestions?