You should be able to increase the fee of your transaction by right-clicking on it in the "History" tab and selecting "Bump fee". Keep in mind that the extra fee will be deducted either from your change output or directly from the amount you sent if you don't have any change. If you are running the latest version of Electrum then you should also see "Cancel tx" option which will automatically double-spend the transaction back to you with a much higher fee. The first option will be probably better in your case. What fee does your transaction pay?
I think providing the transaction hash (txid) will be appropriate, or Sauaba should track the transaction on blockchain explorer, because if the transaction is not support replace-by-fee, he will not be able to neither cancel the transaction not pump the fee.