Ebates Will only pay out small purchases Internet

I have made several purchases using ebates, but they have only paid for the small purchases made. I have emailed them on several occasions only to be told they are waiting for a response from the vendor. It has been over a month since my purchase, but they have ben unable to resolve why my ebates for a stove bought at Lowes.com was not posted to my account. Just received my tiny little check...I guess they plan on pocketing the money made off of my purchase. There is never anyone at the customer service number, so I can't ever get a clear answer.