I have a problem with wastetonerbottles that overfills real fast. The customer have to change wastetonerbottles 4 times without having to change the toner.
I had a 2630D that did the same thing but I had every thing set on it to make the best copies possible. The copies looked so darn good on it that I hated to change anything. I would look through your defaults to see how you have everything set on it and maybe print out a status page all and check it with another machine. It sounds like this machine is set for the highest copy quality as possible.