Hi thank you for your question, my name is Steve and I am a fully qualified technician with over 30 years in the trade, I will try and help you.
Your Megane should have a window relay, this is in the facia fusebox and is the one nearest the edge of the panel, the other relay is the ignition circuit one, the first test would be to remove this relay and refit it, this will ensure the problem is not something simple like a dirty connection.
The fuse you have checked should be number 3 in the fusebox, there are also fuses 8 & 9 but it is unlikely that both sides would blow at the same time and so we can discount that as being the problem.
If the relay looks ok and the terminals do not look burnt, the next place to check is the wiring loom between the drivers door and the body, it is very common for the wiring to fail in this area and that will stop all the windows from operating, you need to remove the outer sheathing and check for any broken of frayed wires.
If nothing is found at this stage then it may be the main switch pack or possibly the multifunction control module, but this is less likely.
I hope this answers your question but do please feel free to ask me any further questions.
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