Good Luck, try with airline site then, see how the after service in case if you want to do a change or a refund.
I always fly with SQ and buy tickets directly off their site. Just as Covid stuck I had CMB-SIN-LHR return (for the three of us) and a also another booking for another destination with them. Then also had LHR - KEF (Reykjavik) return booked direct from Icelandic air.
SQ returned all what I paid - not a
cent charged as admin fee for both their destinations (also I paid for Premium Econ upgrade as well for SIN-LHR, also fully refunded) without a question being asked.
Icelandic Air issued me with a voucher valid for three years and extendable further depending on Covid. I used that voucher in 2022 June to visit Iceland - got the same flights and the voucher covered it in full.
My friends who used travel agents didn't receive the money for two years. Actually though SQ refunded the agents they didn't pay immediately.
I accept that it's messy if you deal with eDreams, Skyscanner and other booking engines. You can't contact them in a hurry at all. OTOH if you book with an agent then SQ doesn't entertain you. They ask you to contact your agent.
Also sometimes the airline direct could be cheaper. For eg in 2022 June we booked from CDG (France) to Croatia. I booked from AirFrance direct, no booking fee, no credit card fee and my friends who booked from eDreams paid more than me because they add various charges.
I prefer the airline because I can talk to them anytime for any changes, rather than booking engines.