A cleaning could just mean a spray buff, coming in with an autoscrubber, or doing a little buffing with a red pad on a 175 machine. You can clean without stripping and waxing.
For simple buffing and cleaning, I charge 12¢ per sf on jobs larger than 2000 sf, 18¢ 1000-2000 sf, below that, I charge what is worth my time and gas money. Someone in the area could pay quite a bit less than someone across town. I add 20% more to burnish with an UHS machine, but only if the type of wax supports that. There are even differences between burnishing waxes, depending on the amount of wax solids and types of polymers used in the formula.
Go to a Walmart or any 24-hour grocery store after midnight. YES, there is cleaning, buffing, and burnishing without a complete strip & wax.
If you don't know the difference, you will damage the floor. Also, if you are stripping and waxing without knowing the different waxes, including levels of care and maintenance, you are doing a disservice to your customers.
Consider the money from this job that you may have missed out on by not knowing what you are doing, the money you may have spent on repairing or replacing this customer's floor because you didn't know what you were doing, the number of times these situations might happen again until you know what you are doing, and the positive or negative reputation your business is building. Don't you think it would be worth spending the time and money to take some classes?
I agree with Kenny. A lot can go wrong with waxed flooring. There are waxes for every need, each requiring a different maintenance plan. Here is a link with some great information, but I still recommend taking a course with someone who has lots of experience.
I like to clean VCT with a Gekko hard surface tool with a brush head and about 600 PSI. If it looks real dull when done I will burnish or apply a new coat of wax.
If it looks real beat up and yellow looking I think it's time to strip.