MX5 NC – DSC uses way too early

Hello! I had new tyres (Hankook) installed at the rear and had the track adjusted again. After that the DSC started in every reasonably fast driven curve. The workshop (not Mazda) then checked the track measurement again and changed the tyre mark to Dunlop. After that it seemed good – but now it occurs again from time to time and the road position is also quite “swimming” even on a straight track at higher speed. My workshop is with its narrowness at the end and send me to the Mazda workshop. On telephone request at 2 workshops, however, this problem seems to be the first and correspondingly the statements (“can you do nothing”, “is there different scope of the new to the used wheels ahead”????) Can anyone give me a tip from you? Does anyone know this problem and where it comes from? Thanks for help / hint! Andreas