Contract changed without my permission

Today I went to upgrade contract after seeing the 10.5 + 5gb promotion. Git to the shop, did everything. Got the router and was told I can a second sim to use on my old mobile router. She teid loading the second sim, she couldn't. I was advised they have a problem with their systems. I should come on Sat for the second sim. Two hours later she called me saying There's a problem with the second sim I might not get it. Can she change my contract to something else over the phone. I showed no interest. . I asked why she doesn't contact Head Office if she is unable to load the second card. She told me Head Office takes long to respond they might take long to sometimes they respond after two weeks and I won't have access till then. I told her its fine coz I really want this deal I am willing to wait. She tried to convince me again, I told her to give me until tommorrow to decide coz I aint paying anything extra than R199. When I got home I plugged it and it worked. After an hour I checked available data. I was shocked see 5gb instead of 10gb. I called the call centre Inwas advised it has been changed to 5gb without my concern. The contract Insigned for is for 10 +5gm thats *****!!!