because i have hard that if the transaction is not get confirmed in 3 days it will expire & the sender recieves BTC back in his wallet
it it true ?
yes.
if yes then what can i do about it ?
i already provided goods in exchange
1) post the tx id here, some folks around here might come along to help nudge it forward if there is no particular issue with it.
2) ask the sender to resend it again when it returns to their wallet and cross your fingers.