Oh yeah I had the same issue with those pads especially since I sweat a lot I ended up ordering some Chinesium brand off Amazon and the first pair had one that just refused to fit it was slightly incorrectly sized so Amazon sent a replacement they fit fine but yes unfortunately those pads get worn real quick and the official Sennheiser replacement ones are expensive even today
On an unrelated note if you happen to have any headphones you would suggest to add to my collection that are good in the same way those are let me know