Agency Travel Rate Quoted - not honoured

On the 19/01/2018, I received a screen shot quote from Pentravel for a 3 night MSC Cruise. Due to the very good rate, I rejected another quote from another Travel Agency. When I phoned Pentravel to speak to the travel agent that sent me the quote, their phones were faulty and I had to send an email to request a call-back. When the travel agent phoned me back, I asked her if she can apply my MSC Voyager number for a further discount. She said she would make contact with MSC, and send me an updated quote. To my surprise, the quote was MORE THAN DOUBLE and increased from R4510 for the cabin to R10 326! She then "explained" that she gave me an Agency Travel Rate and apologised. This is unacceptable as I have rejected another, now cheaper quote, based on her quote. A fault on a Service Provider's side, should not have a negative bearing on the customer. I then made contact with Customer Service and the lady said she will get that branch's manager to phone me. Well, she did, but she could offer me a little discount and the price was then still way over R9 000 !!!