Annona reticulata?

I bought a new fruit today. Custard apples were on sale, my local market proclaimed! From £2.49 down to 99p - practically a steal!

Now I've never actually heard of a custard apple before, but based on the helpful panel tacked to the box they were in, I'd have had to be a fool to not buy a custard apple. Why, according to the sign, these babies:

a) help in neutralizing free radicals
b) are good for hair, eyes, and healthy skin
c) relax muscles
d) can be applied on ulcers, abscesses and boils
e) treat dysentery
f) serve as an expectorant
g) have insecticidal seeds

...and so much more!

They're basically like healthy magic, for less than a pound. (I mean, they're not healthy for the insects, obviously. But they'll basically cure everything else)

Upon getting home from the market I eagerly looked up custard apples on Wikipedia and found out it's the common name for annona reticulata, generally found growing in Central America and Southeast Asia.

Only...hang on, the fruit I bought doesn't look like the picture on Wikipedia. ...Nor like the photos in Google images. Nor....come to think of the picture on the magic-proclaiming sign itself. And...continuing with my cracking investigation here, when I cut it open, there are no insecticidal seeds. More like one giant, probably-not-fatal-to-insects pit.

Yeah, that's a mango. I bought a mango. For £2.49.

I just hope I don't catch dysentery now.