Chsanders

I have a 2008 Ford Fusion just last Friday I had to replace my alternator one of the belts and get an oil change cost me almost $400 today my car started just fine no problems battery light popped on for like maybe 10-15 minutes I went on about my day park my car at my mom's house and spend some time with her and it was maybe sitting for two and a half 3 hours I went to leave and my car wouldn't start it wasn't clicking or anything like that it was just trying to turn over like normal but couldn't completely start does that make sense? I took it to the place that replace my alternator and the belt and they check the alternator the alternator sign they disconnected the alternator from the battery and tested the battery and they sent me over to Interstate Battery to get a new battery I had them check everything out I said how much new battery cost that I wouldn't need a new battery but the battery was fine and it started up just fine for them and they start nothing wrong they couldn't find anything does anybody else have this problem or does anybody else have any answers because I can't afford to not have a car