Charged additional fee due to Mango's website being offline.....****************

I went onto the Mango Airline website to make a booking for flights to Durban. After selecting the flights, the website gave an error message and I could not book the flight via the website. I phoned into the call center and they confirmed that the website is down and that their IT is working on it but could not confirm when the website will be up and running again. I then asked if I can book the flight via the call center. When confirming the price of the flights, they confirmed that there was an additional admin charge due to me making the booking via the call center. I feel that this is unreasonable to have a client pay for the admin fee of booking via the call center due to the website being down and hence the reason why the call center was phoned and a booking done. The error was on Mango's side so why have your clients pay additional charges for the booking. When speaking to Philiswa, the Reservations Supervisor, she just kept saying that I either pay the additional admin fee for the booking or wait until their website is working again which no one knew when this will be. I had to make the booking as this was for a business trip but I feel that a refund should be done of the admin fee as they are now charging a client more because their website is offline.