I was living abroad, 1st I knew of it was when I applied for a loan and was rejected

Hi, I am a leaseholder of a flat above a commercial premises. I have a 3 year old CCJ against me for damage made by leaks from my roof terrace to the property below mine owned by the freeholder. There is no repair covenant in my lease and he has so far refused to sign a deed of variation to change this. The CCJ has ruined my credit history, I have moved out of London and I cannot rent a property in my name, get a mortgage, or a loan etc with a CCJ on file. It's been a nightmare. I'd like to add that I have fixed every leak even though I am not legally obliged too. Is it too late for me to get a 'stay' on this or make a counterclaim for the trouble this has caused me?