vacation time

I would like to know if any else has this problem- When I put in a request for vacation I am told not to request time during the summer or the holidays because management wants to reserve that time for people with families ( I am single ,No kids ) this is fine with me I don't mind taking my vacation in March or October or one of the other off months but now many of my coworkers are demanding they get preferential treatment and get time off during the off months if I refuse to give up my vacation days during these months management has talks with me about my suddenly" poor performance " this problem goes away when I agree to give up my vacation days . To make matters worse management has ripped me a new opening for not using up my vacation days