No exchange of phone

On the 18 Jan 2022 my sister, my dad and I went to PEPCell in KingWilliams towns and i wanted to purchase a phone for my Dad. So we browse through what they had and decided to purchase the Hisense u40 for R899. I went to the till and Ncesh was the cashier that helped me. She informed me that the original network that the phone comes with they dont have but they only have it in Vodacom. So i agreed and processed everything. Today 19 Jan 2022 Im trying tio insert my dad's MTN sim in the phone and it says NETWORK LOCKED. I called the branch on *** and told the lady that answered the phone what the situation is, she proceeded to tell me that they can not exchange the phone to a different Network because i was told it's Vodacom. I then told her that the cashier never explained to me that by me agreeing to the Vodacom sim, it will mean that i wont be able to use any other network on the phone therefore I wont a new phone or a refund. she was extremely rude and told me they wont exchange the phone. If the cashier had initially explained to me that Vodacom = Network lock, I wouldnt have purchased the phone at all and gone my way or purchase it else where. Lady on the phone was not friendly and rude. I need a new phone for my dad ASAP.