Bad service at Digidoor Centurion

On the 13th December 2019, I bought a couple of garage door supplies from the Digidoor Centurion. After almost a month I realized that one the goods I bought (i.e. safety cables) is actually a wrong product (I should have bought tension cables). However, I made a mistake of not reading the invoice carefully to realize that they have a 48 hour return policy.

When I got to the shop, I met the lady at the cashier to whom I explained the whole story. When I showed him the "wrong cables" she immediately said these do not come from her shop...even before looking at the invoice. Then, she started explaining the whole thing about 48 hours etc...My problem is not in the policy...but the manner/attitude that she showed me. When I explained to her that I accept that I made an error of not reading the invoice but at the same time she also has a responsibility to explain these things when customer buy she insisted that it's not her responsibility.

Still feeling aggrieved I went back home and made a call asking to speak to the manager, and a lady picked my call...and I explained everything that happened...etc. The lady said the manager is out at that moment but she will ask her/him to call me back. I asked her what her name was and she said she is Theresa...I went back to my invoice to check who serviced me and I realized it is the same Theresa. I waited for the whole day for a call from her boss but none to come. I then decided to call head office in JHB. I am still waiting for a call from head office. All in all, is that the lady in Centurion (Theresa) is not passionate about helping people.