In addition to that, Maria wants a battery and I promised to check the sexy shop first. But the sexy shop employee doesn't say anything about selling a battery (per the walkthrough)...so I'm stuck?
EDIT: Found a bug in the script. From line 71 to line 100 in game/SCRIPT/sexyshop.rpy is indented four spaces too far, so if you already have the lingerie, you can't ask the sexy shop employee for a battery.
EDIT: Found the bug with the NTR route with Alvin and Sophia. In game/SCRIPT/sexyshop.rpy, go to line 311 and insert a new line below this one:
``` $ item03ss = False
$ alvin_ntr = 8
```
If you've already bought the lingerie (like I did), this won't fix the problem. You'll need to open the debug console by pressing SHIFT-O and then typing "$ alvin_ntr = 8" and hitting enter. Then hit ESC to close the debug console.