iphone4 - EXCESSIVE data use due to ICMP port unreachable

[boeki]

I would much appreciate your advice. My iphone is using excessive amounts of data (600 MB in under 3 days) without actively running applications. I did a lot of testing based on forum guidance and now used a protocol analyzer solve this mystery. Initially I discovered the issue on 3G, after running into overage turned it off. It's only on WIFI right now and the issue persists.

phone: iphone4 firmware:v.4.1
I did the following already: delete all email accounts, turn-off push, game centre was never activated, no facebook, etc. all social apps are deleted. never used or installed streaming services, unstalled IM's (pandorra), closed all Safari pages and reset history, cache and cookies.

I finally installed a protocol analyser (Colasoft Capsa) and proxy'ed the iphone traffic. It came up with the the following error:

ICMP Port Unreachable - Port Unreadable Type 3
Port: 5353
destination IP: 224.0.0.251

This seems to transfer cause several hundreds MB per day to be transfered (2/3 down, 1/3 up).

I am not a protocol specialist and there might be more contributing to this issue.. Thats just what seem to be obvious as it is an error.

I much appreciate the help of one of you out there that understand the issue better and perhaps have some more protocol experience. I have attached screenshots.
Thanks!

[boeki]

Could anyone help please?
Much appreciated!