How can I make Dellhost honor their guarantee?

Nearly a year ago I began hosting two web domains with Dellhost, a division of Dell computers. For the first two months both sites were repeatedly not available. After two months of fighting with customer service, one rep finally admitted that my sites were run from faulty server that had to be rebooted hourly. Rebooting makes your website unavailable for about 15 minutes. I had my sites moved to a server that works properly and have not had the problems since, however I have gotten nothing but the runaround when it comes to getting credit for those 2 months. When I signed up for service, they were offering a 99.9% up time guarantee. Anything between 99.9% and 85% up time was promised incremental credit. Anything less than 85% was promised full credit. The rep who told me what my problem was told me the server I was on was averaging only 50% up time, which would entitle me to 100% credit for two months. The total credit amount for both domains combined would be about $140.00. I just sent my 3rd e-mail reminding them that this credit has not been applied. They replied as usual, and said it would “be referred to the billing department.” That’s the same pat answer I get every time. I have also asked for a supervisor or manger to call me back, since they are never available at anytime day or night, and nobody has returned my call, yet I am always promised they will. I have cc’d these e-mails to every billing or customer service e-mail available on their site, with no returned phone call. I know that it would cost me more to file a lawsuit than what it would be worth, but is there anything else from a consumer legal perspective that I can do to make them live up to what they promised in their guarantee?

I am in Texas. Dell is in Austin, Texas, but the Dellhost servers are out of state. I'm not sure where. PA, I think.

Time to "move on up the line". Try contacting the parent company-customer support.
I am surprised you are having this problem because my experiences with Dell have been excellent.

Thanks. My work deals a lot with Dell purchasing computers for a school district. It's extremely hard getting warranty work out of them there too. I'll see if I can find some higher contacts.