... I've paid 0.0008 for 0.003 transaction ...
This is pretty much useless information. Fees are NOT related to the amount of BTC transacted. Also, the total fee used is meaningless without knowing what the transaction "data size" is as, fees should be calculated based on the "data size" of the transaction.
This is why people talk about fees in terms of "satoshis per byte"...
sure you used 0.0008... but if you transaction was made up of a lot of small inputs and your transaction "data size" was 1500 bytes... your effective fee was only ~53 sats/byte... when recommended fees are like 300 sats/byte.
You need to post either the transaction ID or tell us the fee in sats/byte for us to tell if your fee was too low or "OK".
Additionally, without the transaction ID, we have no way of knowing other reasons for your transaction being unconfirmed... like unconfirmed parent, double spend etc etc.