I had complained to SQ office in FRA and that is the reply I got from a customer service agent.
“Thank you for your Email and we are so sorry for the inconvenience you had to go through on our website.
You may call us under the number 069 7195150 and we will try to find the best fare for you. Of course we won’t charge you any service fee.”
At least we can call in and do our booking over the phone….