i sent some bitcoins over a month ago now but made a mistake with the fee being too low, its still unconfirmed and i have tried to start bitcoin core using the -zapwallettxes command but it doesn't make any difference.
Well that option should just delete those transactions and not get them confirmed. Since it has been that long, your wallet was maybe the only one that kept that transaction, now it is maybe like it never happened. So you should be able to send another one with a correct fee.