Holes in clothes Candy washer/dryer DWQ150

I have a Candy washer/dryer model DWQ150 which is about 3.5 years old. Last year during the summer months I noticed small H shape holes appearing on clothes – mostly t-shirts. Initially I thought they were due to the lanyards my boys were wearing for their mobile phones…..that is until they appeared in my husbands Lacoste t-shirts!! Winter came and everything seemed ok (maybe because winter clothing is thicker and heavier). Yesterday whilst ironing my new top…worn only once…there were 3 H shape holes on the front!! I looked at other items that had been in that wash and another of my husbands t-shirts had been attacked!! What can be causing this? I can’t find any sharp bits in the drum. I’ve had a nylon stocking on my hand and run it around the drum but it doesn’t catch anywhere and there were no bras or zips included the last ‘destroyer’ wash.. Any help would be appreciated. I am now considering a new machine….Bosch or Zanussi is the next question….Thanks. : 😕