Horrible service from Christina at Levis Atterbury over a jean

On 27th of November I went to Levis at Atterbury and bought 1 T-shirt, 2 jeans and a pair of shorts. I then went to the fitting room and fit the T-shirt, shorts and 1 jean, at this stage I hadn’t found the 2nd pair of jeans (the jean in question) and also only 3 items were Allowed per fitting. Eventually after spending more than an hour I found a jean I like but wasn’t sure if the size so I asked a store assistant what size does she think I am for this specific jean and after analysing my waist and hips she said 29 and also stated that it stretches so I would be fine. So Because of the Black Friday rush and it being very packed and busy and the queues for the change room being long, I then trusted her because she is a pro at Levis jeans I took the jean and went to the tellers paid and left. On the 2nd of December I left for Cape Town for a conference I was organising and only returned on the 10th. On the 10th, I decided to wear this specific jean and I took off the tags then after managing to wear it after a struggle,, in less than 10 minutes I took it off. The waist was so tight it left a bruise on my waist so I took it off immediately packed it and the tags in my suitcase and wore another outfit. On the 11th of December, I went back to Levis Atterbury to exchange the jean and I was told by Christina that they refuse the exchange because it was “worn”. I explained to her several times that yes it was worn, I had to wear it in order to realise that it’s not my size but it was worn for less than 10 minutes. She kept repeating this and saying that the tags should be on the jean and I asked her whether she wears her jeans with tags or removes them when she’s gonna wear them. She kept mumblinb and I left. I have the receipt and tags and this extremely uncomfortable jean that I want to exchange to a 30 that’s all. She was extremely rude unnecessarily so as I wanted an exchange not refund.