Hello everyone I'm new here and i have a question, i've send btc to my wallet on an app (lunu) and it didn't arrive so this is the message they send me:

Dear Customer,

The problem is that you have used a decommissioned app, as you mentioned in the beginning of our conversation.

We never got the amount you have transferred.

We would like to advise you to export the raw key with your Lunu wallet konfigurations to get a possibility to forward your amount back to your personal wallet.

Kind regards

And they also told me to import my private key in raw format but that's not working anywhere maybe someone can help me out