Expensive summer bag - Sierra Designs Backcountry Bed 650F 20 Deg Sleeping Bag

I wanted this bag to work SO BAD! The design is exactly what I’ve been looking for since as a side and stomach sleeper, I hate mummy bags. Unfortunately on its maiden run in the Monongahela Natl. Forest this bag failed miserably to perform. Our coldest night was 28° and the average temp hovered between 30-35°. I purchased the 20° bag and had high hopes only to find out that my $300 investment would be utter trash. I shuddered myself into fitful sleep and shivered myself awake over and over and over, for 5 days straight. The side panels have ZERO down in them. Every time I’d turned over I could feel freezing air seeping into my backside and legs. We took a look at it in the morning and sure enough! The sidewalls of the bag were pretty much void of any fill. Maybe it’s a manufacturing defect?? My brother (who is a hot sleeper) traded bags with me so that I could get some rest on day 3, and he experienced the same miserable performance only with less extremes since he’s always running warmer than me. I purchased this bag in August and didn’t have a chance to use it for winter hiking until February, waaay past the returnable window. I’m going to try to take it up with Sierra Designs, but I’m sure I’ll be stuck with this VERY expensive warmer weather bag. I’m totally bummed, and wary of purchasing anything winter related without testing it immediately, which kinda limits my purchasing window in the future.