The best thing to do is to visit the accounts office in your KMTC branch to have the issue addressed. KMTC Commitment fee is supposed to be part of your school fees.
Make sure that you have all the payment records or evidence to make it easy for the accounts office to follow up on your case.
Obtaining Payment Evidence
If you paid via Mpesa, then you can get evidence of payment through your mpesa statement. Mpesa statement for more than 12 months can be obtained by visiting a Safaricom shop near you with your ID.
If you paid via Bank, go to the branch where you made the payment and request for a payment receipt to be generated. They can use your ID number to search for payment.