Heating (PL1)

Looking for anything that may keep me warm in a flat that doesn't hold any heat. I've 2 heaters that aren't doing much at all and I can't afford to buy more than I have I've a king sized bed and loads of blankets but I can't get my flat above 5°c even with my heaters on most of the day :( I've complained so any offers with anything that may help I'd greatly appreciate, I've blackout curtains, 2 heaters and rugs but none of that has helped.