I got a customer who has 2 acres. The back acre they only want to mow once a month then mow the front when they call. I told them $65 for the front and 20' out the back door, then $100.00 for the lot. Well needless to say I wasn't expecting them to only mow the back 1 time a month. By the time I mow it it is a good foot tall and takes forever. What should I do? Tell them it is more if it is only 1 time a month, or just eat it?