bad service and product from AMC

I brought an AMC 8L speed cooker, I have used it once to cook pea soup in it. after just one cook, the inside of it is streaked and stained. I went to the AMC office DC in Randburg today and the receptionist was extremely rude, dismissive, unwilling to help and advised there's nothing she could do to assist, that I must go back with it and clean it properly. Mind you, I have another exact same pot which I've had for over 4 years, using it regularly and have never had this kind of problem. the pot I took in today is brand new.

Can someone please assist, this pot is expensive and I feel this is unfair and would either want this pots streaks and stains removed or the pot replaced.