I bought a bag of dogfood that's full of maggots and insects

Hi,
Just wanted to seek legal advice about this matter.
Bumili po ako ng dog food, this is a dog food that my dogs really love. Ngaun, nung pagkabukas ko, puro siya uod at insects sa loob together with the dog food. Gusto ko lang po malaman kung ano pong laban ko dito at magandang gawin.. hindi po siya expired at lalong wala din pong penetration yung bag, and even so dalawang bag po yun so hindi basta basta mapapasok ng kung anonh insect. And take note this happened twice already.. nung una, pinalagpas ko lang at mano mano kong tinanggal yung mga uod.. dahil sa di ko naman ugali ang magreklamo.. pero this time, sobra na it only means one thing.. may maling nangyayari... please help me, nakausap ko na po yung marketing ng mall, at so far ang gusto niya lang gawin ay palitan yung binili ko... is that even enough? Would I just let it pass ng ganun ganun na lang? Thanks in advance.
I'll try to post photos if possible.

if that's not enough for you, you can file a case for damages in court.