You might be cold but at least you're not laying under a 10 year old comforter not laundered in 4 months that's been through 60 guests, spit up, baby poop, spilled soda, wet towels, etc etc etc

And as someone who worked in the hotel industry, I can assure you 4 months is about the average time in between washings for those old bedspreads.
Housekeeping does have real blankets, just not sure how many. For future reference, stop by the front desk and request one rather than calling. You could also try to catch housekeeping near your room during the day. You could also leave a note with a $5 bill asking for one. If they don't bring you a real blanket the first time around, push back. Sometimes it takes a few times (unfortunately) to get what you want.