Website error lead to double booking - not refundable

Tried booking a flight for my husband for Saturday via the website. After loading the card details for payment, the website said that my request couldn't be processed and to try again. I tried again, it still gave the same message.

I then proceeded to book directly from the various airlines.

Later in the day I noticed emails from travelstart with the eticket details.

Emailed them to please cancel the booking and received this response: "Please note that the first flight which is with Flysafair this booking is a low cost carrier and this flight is non-refundable, only changes are permitted- this must be done at least 24 hours prior to departure."

Now I have to pay for this flight and it was their website at fault.

I will never use their site again and I will never refer anyone to use it.