What does mean "mobile credits"? Do you mean a mobile wallet or mobile balance that exists in your sim card? If you are looking to buy bitcoin with a mobile wallet then likely you have to choose peer to peer exchange or person. If you are looking to buy bitcoin with sim card balance then likely you will not found such as service. You should look for alternatives ways, but avoiding KYC to buy bitcoin with credit cards or through banks is quite complicated. You may look at the forum Currency Exchange section, you might find someone from your country and you can exchange BTC/mobile credits or bank transfer. Don't forget to use escrow service if the seller isn't trusted enough.