I would just say that i realise times may be tough. I want to remain a good customer so if i can help by paying more just charge me more and let's be fair and honorable to one another. Cool?

That's the way i would put it. I wound not necessarily pay more, but the statement would be there to put the person at ease and extinguish any fires before they start. You have to stear discussions in the way so as to not allow any negative thinking to set in on the recipients side. It's a game of compensating for the other persons preception of what and how you're saying what you're saying. So don't accuse and make like it's an honest mistake.

Hope i made sense.