Bul**** by shell garage

I went to Shell Garage in Pietermaritzburg Victoria Road where I purchased my car's headlight light Bulbs, one bulb wasn't working when I try installing it into my car. I tried to return the unworking product to the garage and they refused to do exchanges and also refused to refund me my cash which made me feel so bul****. I requested Branch Manager's contacts but tellers refused to provide me. I was so abused to the fact that I had to drive 20km home at night risking my life and other road users's lives. They told me to drive my car as is or come back tomorrow to report the Matter to the branch manager. shell Garage has no 24 hours emergency helpline.