Guest reached DMK by themselves but very disappointed with the service. For now if you may trace the guest then please try to refund the taxi fare to guest & try to settle the case here itself before the guest could reach to India. Also if you could arrange the refund for the taxi then do take refund acknowledgement from the guest in order to have a proof.
But this is a big mistake & your company have to prepare for compensation that we don’t know that expectation let’s hope that the guest won’t ask for much other than the taxi fare.