Contast pain in my knees

I have previously owned a pair of Hillwalkers and a pair of Superlites and been completely satisfied. I then bought a pair of Hillmaster boots. I walked in them every weekend (and some weeks) for two years. After about three months I developed terrible and constant pain in my knees. Went to to doctor but they confirmed it was not arthritis. Towards the end of November I stopped walking and the pain went away. I then did one walk in my Hillmasters and the pain returned. I have contacted Brasher to see if they could make any suggestions but their response was "we only produce outdoor footwear". I had also recommended Hillmasters to my partner and his heels have been ripped to shreds - and he, like me, will never buy another pair of Brashers.