You have the perfect opportunity to raise prices- send out a letter saying economy,ever increasing labor costs, fuel etc.... and raise prices $5 a week to "help" offset your costs.
if you have 3 trucks going I assume you have over 100 accounts, so $20X100 = $2000 bucks a month if 10% drop off then you are still ahead cause the rest are paying more and you don't have the expense of those 10%
For the "nay sayers" if the OP is making no money, what's he got to loose?
People seem to think that if you loose a $150 account, that you're loosing $150, but what you're really loosing may be closer to $60 because of the cost involved to care for the account.
Especially if you do good work, if your guys do a crappy job, then reconsider price raising, but if the quality is there, then most people won't hate you for it, and $20 is not usually enough for most people to shop around and use up their time.