So 30M has been paid for DT + Thieving, then the worker realized that Firemaking still needed to be trained which would cost another 4m. There was no timeframe discussed and there was reasonable progress on the account.
@BeastRevelation will need to pay the agreed amount for the firemaking XP and the DT order can be finished. He will not need to pay for the MM order as it has no relevance to his original order and was just an add on.
There is not enough here to warrant a refund on a no-refund ToS.
As discussed in PM, the service provider has time to complete the service. You cannot just cancel a 'no refund' service for no valid reason. @Diete has also offered a 50% refund on the incomplete service minus the skilling.