Hopefully i can help..
Firstly check the bulbs and ensure the bulb filments arent shorting - you could try replacement bulbs and see if that helps..but you could also to eliminate the area you need to investigate by disconnecting your rear light clusters units, "bear in mind your high level brake strip may still come on" so you could try and disconnect that too if need be - replace the fuse and try the brake pedal if the fuse blows the fault is between the pedal switch to the rear clusters.so it going to be a bit of time tracing that wiring back, if the fuse doesnt blow the short is in your rear clusters or the circuit board/bulb holder,,connect one and try the brake again - if the fuse still doesnt blow then the one still disconnected is most likely at fault..ensure the plug connection to those clusters isnt corroded so carefull check the pins of that..I do hope this helps
sorry its took so long to get back to you i am not very well at the moment, i should have tolded you that i had tryed disconnecting them one at a time i disconnected them all today like you siad and it still blows the fuse thank you back to me
..there thanks back to me..
Ok..aswell as the high level brake strip disconnected? - if thats the case and the fuse still blows with both clusters disconnected ..then unfortunatly that means the problems in the wiring loom from the clusters back to the switch or the wiring from the brake contact switch back...i d say the next step is to trace the wiring from the rear clusters and check damage..or exposed wires shorting to ground..check the ground points /brown wiring at the rear ..also if you have towbar fitted certainly rule that out as towbar electrics can cause heaps of problems especially if diy fitted etc..sadly by the sounds of your description its going have to be a trace of that wiring