Bumber to bumber refuse to assist

I purchased break discs which were incorrect. I returned them within 24 hours however lost my physical receipts. I clear full copy was available which I sent to the machanic at the time of purchase. The staff member advised I should talk to the manager Brandon who could assist. A digital copy of the invoice as well as the new breakdisc were shown to the manager who rudely said he cannot assist and walked away. I was forced to purchase the correct disc and now have another pair of disc with the copy of the invoice whereby the company refuses to assist. I am a long standing customer to this extreme busy store, however I feel as a consumer we should be at least heard instead of being shuved in the corner. I'm sure there is some sort of consumer protection we can seek assistance from.