i have an unconfirmed transaction (i assume due to selecting lower mining fees). repair wallet doesn't do anything. is it true that after 72 hours the attempt will cancel and the sender will have the money back in his wallet if it stays unconfirmed? what should i do?
Yes it's true. You should wait 24-48 hours more and try repairing the wallet again. The "Repair Wallet" feature only remove transactions that have been dropped.