In my opinion your rate is too low by a third, and you should not refund them. If after 3 months effort, doing the right things, they are not at the top, someone is simply better optimized than you are or have a more authoritative site than you. You can only take them as far as they can go.
My pitch for google places to the customer goes along this line.
You need to be on Google places and I can optimize your Google places listing to get you the highest rank possible. The best you can hope for is spot one, bu because Google is always in flux and your competitors want that top spot too, no one can guarantee the number 1 spot with absolute certainly.
I will be able to bring you company as high in the places results as possible, and it may be number 1 or it may not. Either way, myworkload is the same, and I charge a flat rate for this service. Your results may vary. There is no way to predict what google is going to do at any given time. I can provide industry standard services for your company, then just like like everybody else, we are at the mercy of the search engines.
I will however also do this for you. I will not optimize any of your competitors listings. You will be the only <whatever> I will optimize in your neighborhood.
i also bindled some other marketing services for them too. The only reason I guarantee first page here is because I know I can deliver in less than 2 months. And looking at the competition very likely to be top po.