Silver Angel - What a nightmare but please take heart!
If you go flight only and get a cab from the airport to the taxi stand at Calangute, you can then get a local taxi driver to drive you around the area you want to stay. He can knock on doors for you and see how much and what the place is like. We did this in November and ended up with great accommodation, close to the beach.
The season is not busy so there will lots of rooms available and you can take your choice and do a bit of haggling. You may have to be firm with the taxi driver because he's likely to take you somewhere where he can get a bit of "commission". Just explain that you'll look after him if he finds you somewhere good and inexpensive.
I know it's nice to have everything organised in advance but I'm equally sure you will find something that is likely to be as good, if not better, than what you had booked. After all, if you don't like it, you don't stay there.
I hope things work out for you and you have a great time!