Very bad, disrespectful and unprofessional

I visited Hi-Fi Corporation in Mams Mall in Mamelodi. I asked for a pedestal fan with a price tag of R699.90. The fan was sold to me for R799.90, when argued that, I was told nothing can be done, it's either I take it or leave it. I complained all the was to the Security. She (the security) told me, to tell the Manager (Timothy , his name) and I did and he just laughed at me. I left the shop as their laughing stock with other staff members.