I've been fighting with UPS since March. They too were charging us more than was stated on our software.
I informed my rep that I would not pay ( just over $3,000) the bill until the credit was received. He came to our business, agreed it was their mistake and told me he'd take care of it...never did. I called him several times and informed him I haven't paid the bill and another had arrived. I got another UPS rep involved and he finally straightened it out, but I was set back 3 months of bills which totaled just over eight thousand.
Since then I paid all but June and July and have been cut off, without service for our business. Had the rep done his job I would not be in this predicament. 95% of our work comes in in a box and leaves in a box. I feel UPS is only in it for the money and service has gone down hill.
I don't have a problem with making a profit, but don't gouge me. FedEx is looking mighty good!