Missing Rheem / Dishonesty by staff member

It is with great disappointment and shock that i'm writing this.I bought 4 tyres in February this year. One of them tore on the same day and I went back to Hi-Q in Mooi Street for assistance. They assisted me by changing the tyre for me and putting in my spare wheel (She,the lady assisting me, took the torn tyre together with the rheem ,It took them 10 months and a complaint to the Head Office to get the new tyre back.Unfortunately for me i'm not clued up on tyres or cars,hence I trusted HI Q staff to assist as a customer. So it was a shock when my fiance told me that when he bought me the car all 4 tyres had original rheems ,so the rheem i left at the shop with the tyre was the VW original rheem and not a wheel cap as I thought. Everytime I called and went the to the shop (During the 9-10 months period) to fetch the rheem (or wheel cap as I thought)I was told they don't know where is it and that it's missing . I want to know what happened to my original rheem. and I want it back .Where is the honesty and integrity???? I will definitely be opening a case against Hi Q and the staff member if I don't get feed back soon.