Which part of the world are you in? Here in the UK I called their Southampton office where returns go to and asked them to confirm receipt. The guy physically went to the mailroom and checked they had it.
Alternatively, if you E-mail [email protected]
, you seem to receive a swift reply and its much easier than going through the regular channels of communication . I'd quote your RMA number when replying.
You can also use the Repair Status checker on Archos.com but it's slow to update sometimes. Better to try the above.