Well lots of companies give money to charities and don't make big deals about it.
And I agree with Nieur anyways. Per a related article on theregister.com their rates are also 20% higher than the competition, so
Company A: Bills you $60 for service that costs $50
Company B: Bills you $72 for service that costs $50 and then donates 25% of the difference [$5.50] to charity.
Why not just go with A and give $12 to charity rather than giving B $12 so they can give less than half of that to charity?