Can my employer shave time off the time I turned in?

I work for a property management company and we go on various different jobs throughout the county and have to turn our time in via email. Every week when we get our paychecks, we get a print out of the time that we are getting paid for. I decided to go back and check the time and I noticed that some of the time that I sent in has been changed. Is this legal for the employer to do this due to the fact that they didn't have enough money in the job or they think that we took too long? Also, since im the nephew of the guy who signs the checks, then I am entitled to pay, correct? Please let me know what you guys think and how I should go about this matter. Also, I have brought to their attention that my hours are not correct every week and they keep saying that they will look into it and put it on my next paycheck. But nothing happens