Iphone problems

I have a problem with my Iphone 11 that I sent into the Waterfront store for diagnostics - they found not fault but my phone is slow and giving me a lot of problem. The phone is not a year old yet.

Let me explain to you what the problem is: 1) I download my backups last night, it took 11 hours for WhatsApp to download. a. I used a Iphone 6 as my backup phone and it downloaded WhatsApp within 2 hours. b. The full backup took from last night 8h till 7h this morning – this is too long Donovan. 2) Phone calls – any phone call I receive the person on the other side waits between 5 and 10 seconds before they hear my voice. a. If I press the receive button the phone still rings for 3 to 5 seconds before I hear anything and can talk to the person. b. This is not good for my business Donovan. c. Please let me know when you can phone me and I will show you this problem. 3) Voice notes – I press the button and then it takes 4 second before I can record the voice note. 4) Itunes – this lags every now and then.