Cannot Purchase App, Help

[Guest lordjubblydave]

I downloaded Tune In Radio Pro via Get jar.

I now want to purchase it from Google Play as it is on offer, the problem is Google play will not let me, t only gives me the option to download it (as if I had already purchased it)

Then if I try and download, itgets denied with an error message saying that I have not purchased it.

Which is true, but I have no option to purchase.

Anyone got any ideas ?