Nu Metro & it's incompetence

I had booked tickets for 50 Shades of Grey 2 weeks in advance for Valentine's day for my girlfriend and I. We went into the cinema and looked for our seats only to find a African lady about in her 30's occupying OUR PREVIOUSLY booked seats. I asked her nicely to please move so we could both carry on with our respective nights and not disturb anyone. She refused and stayed put. I went to the concession stand and ask for a manager. There was none on duty. So a Nu Metro staff member helped me. She then spoke to the lady in a language they both spoke (guessing it was Xhosa) and then the staff member just left me! I had no choice but to take up other seats that was booked by another couple. We then moved, again. Where were the ushers or necessary cinema attendants? I paid for a service and expect to be seated where I want to be. Where I book! Furthermore, I have emailed and phoned and have had no response. I'm very disappointed. And will not rest till this is dealt with. My girlfriend & I didn't enjoy our cinematic experience.