I was booked PYE JFK-SIN and SIN-JFK. They contacted me with 4 options:
1) Downgrade to economy, inflight vouchers (I think $150 per leg, don’t remember), and EY to PEY upgrade voucher
2) Rebook flights to a later date on a flight with PEY, and EY to PEY upgrade voucher
3) Upgrade to Business Class at a discounted rate, and EY to PEY upgrade voucher
4) Full refund without penalties, and EY to PEY upgrade voucher
SQ customer service is not all on the same page. I didn’t make my decision right away and had to call them back. I decided on going the upgrade route, but between the 4 different people I talked to, I got slight different stories of what it would cost me. In the end it cost me an additional $300 per leg ($600 total) to be issued a U class round trip ticket. Better than I’d expect from SQ, though not as good as what other airlines would offer.