I sent in rebates for a 30D and a 135MMM EF L for a total of $350 on March 19th and got my reciept confirmed by the Post Office on the 3rd of April.
Based on advice here I photographed everything as well as made copies.
I checked the rebate web site tonight and was told that there was "missing warrenty information" and a check for $25.00 was being processed.
So, I called the Rebate Center (1-877-862-6870) and spoke with a very pleasant tech support person. I explained the problem, reviewed the backup documemtation I had, and asked what was needed to get things corrected. I was put "On Hold" for about 5 minutes and then the tech person came back on line and told me she had found and corrected a "technical error" in my claim and that I would get a check for $350.00 in about two weeks.
Keep your fingers and toes crossed
I'll report back when the check arrives.
I had similar problem. Mine was $190 on a couple of L lenses. First they said they did not get UPCs, which i sent. Then they sent me a check for half. I sent email to Canon and they agreed it should have been $190, and said the other $95 would be coming