I think builders is a no no service is poor they promise to assist when u leave they forget about u

I’m in contractions I bought a grinder at builder Phola mall in October only within 30days it was not working anymore I return it back to the store they promise to check it now it almost a month without any positive respond is lying in the shop I had to go to took hire hoping it to be fixed now I have an invoice of R1900 for hiring the tool after I bought 1 from builders so devastated why can’t they check the fault or replace it I use grinder 80% in the work that I do