The key here is to be presistent, keep sending GW letters, send them one a week regular mail, they will get tired of hearing from you and eventually delete.
The trick is to send the letters different everytime so they don't just look at the envie and toss it.
Example, letter one, hand write and send CMRRR to make sure you have to correct address and wait for a response, if they don't delete send another one every week, make the next one in a small envie, fold the letter up so it is bulky and gets their attention and they want to open it.
The next one send with a printed address label no return address but do include your return address INSIDE the envie on the new GW, change the GW around a bit so it doesn't read the same, Co's HATE form letters. Keep doing that in a different way each time.