Please advice-is there an office to which a Visitor Visa Rejection complaint can be sent to? It's for a UK Visitor Visa rejection.
Should you wish to lodge a formal complaint, the appropriate government department is the Home Office at 2 Marsham Street, London, SW1P 4DF. Its response would likely be a form letter from the correspondence unit advising you to make a fresh application.
Before doing so, please understand that permission to enter the UK, or any country, is not a right or entitlement for those who are not its citizens. After two unsuccessful applications, the best course of action would be to address any issues or shortcomings noted in the refusal letter(s).
Without seeing the actual notices, and the section(s) to which the refusals were cited, here are several comprehensive Q&A's that might be helpful:
And, as @Traveller suggests: