Help at the Post Office, mass letter sending (Haag, NL, 28.07) - Repost - open to bidding

Hi! I'm looking for a RESPONSIBLE, adult person, who will be able to help me locally in Hague. 200 EUR for one day of your help. I am managing a project for one of our clients (we are an Advertising Agency). The task is to handle sending a traditional paper mailing campaign (printed letters in envelopes). I need help from someone local from Hague to assist me and translate everything at the Post Office, basically get the job done. I will need an invoice (if possible, not needed) and i will be paying with cash. I will have around 7000 (seven thousand) letters to post, each at the rate of normal, untracked letter (what's the price of a standard local stamp in Netherlands now?). I'm offering 200 EUR for your help, everything shouldn't take more than a couple of hours. I will personally be there with the letters, but i don't speak Dutch, so i need you :) In order to prepare for this task please find out if we will need anything in particular before we can post this amount of letters. The post office need to be capable of accepting letters in bulk and using a franking machine. Perhaps it will be necessary to go to several post offices instead of just one? Are there any post offices open 24h/7 in Hague? If buying 7000 stamps is also an option, i will have some people to put them on the envelopes if necessary. I will arrive on Friday next week (28.07). In order to properly prepare for this job, you will need to find the right Post Office branches, call them or go there personally, ask if there are any limits for sending the letters (letter amount or money limits), also find out if it's possible to pay with cash only, and can i get an invoice for a UK company? Please only apply if you are available throughout Friday.