Disappointed

Good Afternoon!

I am contacting yourselves in regards to my IPhone SE. I purchased it back in April and for the first few months thought it was fab! However my phone has deteriorated since, things including my screen freezing, battery life, charging port, camera and how much slower it seems to run. I love iPhones and that’s why I looked into this one. Can you help me in regards to warranty? Do I need to speak to you guys or go through the business who I bought it off?

I look forward to hearing from you!