Red Brake warning light displays constantly

Audi A4 2002 2ltr - The orange brake pad warning light on the dash came on a week or so ago and so I got my front brake pads replaced. Every since then the red brake warning light has been on and if I press “check” it displays “stop vehicle check brake fluid and hydraulic fuel levels”. I’ve checked the fluid levels and they’re fine and I've disconnected the battery to reset the sensors but it still comes on. The garage has assured me that there’s nothing wrong with the brakes or the sensors and they can’t see why it’s coming on. Has anyone else had this problem or does anyone know how to fix it?

Keep adding DOT4 brake fluid to the reservoir.

check to make sure your tail lights are working.......red brake lights are activated when there is a fault or a light is out