Seamstress - restitching 150 pieces of underwear

Hello,
I am launching a new brand of mens underwear. I have had a first order manufactured in Portugal, the stock is now in the UK, I have to deliver it to the customer Friday 28th Jan.
But one of the seams of the briefs need to be slightly corrected (the sitching on that particular seam, between the legs, is a bit too bulky - it would need to be top stitched, to make the inside of the garment more comfortable).
So I am looking for a seamstress, with own equipment (to work on jersey fabrics), to do this work, on approx 150 briefs. Preferably based in or around London. Free to work within the next few days. Ideally the person will be able to meet me in Central London so that I can show a sample and explain exactly what I need (I will pay for travel expenses and travel time). I will then arrange for the briefs to be delivered to you.
Thank you