Hi Omkar!! I would like to inform you that challan is for your reference.You can mail your concern at the KCET official contact details as they can only guide you with best alternate. The challan is important documents and is helpful in the verification of your candidature so if you don't get any response from them I will suggest you to contact your bank ( the one you paid the fee in) they might try to help you out.

Hope that helped.Thank you