App crashing and missing purchase

After being nagged several times, I finally accepted an in app "unlock all" purchase. I accepted but did not receive my purchase. I did however get billed. Now my app will not run at all. Apple support, which is virtually useless, tells me I have to contact the developer. The developer (Agile) will not reply to my support requests. Apple does not appeared to be overly concerned. This is rather unfortunate because I did like the app. Buyer beware!

JourneyEclipse about GuitarToolkit - tuner, metronome, chords & scales, v2.5.2