I want my airtime back not this ***** OF DATA UOU GAVE ME .

I just bought a R500 air time using my banking app , when I check my air time it says R159 or something remaining how ? Apparently if you buy a monthly data last month Vodacom automatically buys you the same data as soon as you have enough airtime with out you agreeing to it . When I purchase the data last month the was no explanation nor description that’s says this . Can you reverse this I want my air time back and put me out of this ***** you guys do . Give a customer an explanation or opinion to agree to it not you automatically buying for me . Please reverse this *** ASAP .