Re: "Can't set custom ringtone bought from store"
If you bought a song, it may be too long to use as a ringtone.
It may need to be shortened (eg in the free Garageband app) before it can be used as a ringtone.
(Feel free to let us know if you need more help with shortening a song, and adding it to ringtines.)
or
If you bought a ringtone from iTunes, you could try re-downloading it to see if it shows up with the rest of your ringtones, ready for you to select.
Use tones and ringtones - Apple Support
Eg: says:
"Go to Settings > Sounds & Haptics > Ringtones, then scroll to the top and tap Tone Store.
Your purchased tones and ringtones appear at the top of the list of sounds.
If you get a new device or your previous purchases aren't showing up:
tap "Download All Purchased Tones".
You might not see this option if you already downloaded all the tones that you purchased or if you haven't purchased any tones. You might not be able to redownload some previously purchased tones.
Store availability and features might vary by country or region. Learn what's available in your country or region."
Trouble-shooting:
If there's an issue when you redownload apps, movies, or other content from Apple - Apple Support
or Get ringtones, text tones, and alert tones in the iTunes Store on iPhone - Apple Support
Eg: says:
"Redownload tones purchased with your Apple ID
If you bought tones on another device, you can download them again.
- Go to Settings
> Sounds & Haptics (on supported models) or Sounds (on other iPhone models). - Below Sounds and Haptic Patterns, tap any sound.
- Tap Download All Purchased Tones. You might not see this option if you already downloaded all the tones that you purchased or if you haven’t purchased any tones."
Re: " ... they said I should query for refund"
See how to: Request a refund for apps or content that you bought from Apple - Apple Support
