You could try their free service though, only if the tx fee is >= 0.0001 btc. Paid tx accelerator always charge higher fees so 25% is pretty normal. Much better to wait if its not that urgent.
Fee was 0.0006. Cannot use free
Yes you can if its 0.0006 btc. Viabtc free accelerator can accelerate transaction fee with 0.0001 btc or above.
Just a little tip, be ready at 59th minutes of the hour and submit it on hour sharp, hour:00:00 as it accepts only limited numbers.