What can I do after someone denied that he has received the money I?
Sorry to know about the situation you have landed in. But be sure that if there is a problem, then there IS a solution; if there is a question there is an answer - that is how laws of nature work. The need of the situation is to have proper understanding of how systems work. It is possible that the amount you claim to have transferred has not been credited to his A/c for various reasons. Having the amount debited from your A/c does not by default mean it has been credit to his A/c. Hence you can approach your bank and verify/cross check the correctness of the transaction. If you get a positive reply regarding correct credit having been done, you can approach the other bank, placing your apprehensions to them ? They will co-operate and are expected to co-operate. It is like this, i have posted a letter in the box. It does not mean the letter has been delivered. It is possible that the box was not cleared (for whatever reasons), the post man would have misplaced your letter (rarity, but possible); the postman would not have been able to locate the address (rarely). Hence the system of Regd A/d where you can be sure of prompt service. Hope my answer is of some use.