Bad poor service

Good day.. I went to the Fix Somerset mall store...I told the lady that's working in the store that I would like to make an lay bay for 2 items but I want a bigger size.she told me that the size that I'm looking for shows on the system it's on their way.i ask her can I than just exchange sizes, she told me yes..today I went back to do the exchange,the cashier told me that she needs to cancel the full lay buy and start over..I told her it's fine.she didn't explain anything else.. while I'm waiting a 15min for the cashier to do the exchange the manager came and than told me I hade to pay in because I cancel the lay buy. I told her know one told me that I had to pay money in again I just want to exchange a bike size and still keep my laybuy,the started to laugh at me and starting for speak in Xhose language....which I felt so uncomfortable and confused at the same time...as far as I know business language is English. I told them if only I knew I would never do the exchange but no one explain..I paid the money in and left the store.they starting to laugh louder as if I was stupid....while I'm also standing in the Lyn all the customer was asking why there is always a problem and half the customers left they items and left the store..this wil be my last visit at the fix Somerset mall store