Excel Rota Clash Automation -- 2

My offshore personnel rota lives in Excel and has grown into several separate tabs. I need a VBA-driven solution that will: 1. Instantly flag any date clash whenever the same person is scheduled on overlapping days across different tabs... (Budget: £20 - £250 GBP, Jobs: Automation, Data Analysis, Data Management, Excel, Excel VBA, VB.NET, Visual Basic, Visual Basic for Apps)