Verry poor service. Would not recommend using apple services!!!!!

I have been struggling for a week now and been phoning up and down to try and get my phone working After my phone updated my signal just disappeared and i have no signal i cant make or receive calls from that number i did speak to apple and my service provider everything on my service provider side is working 100% i have tries so apple can assist me but the only answer they give me is to contact the service provider then the service provider say i must contact apple The problem is on apple side. I have been using that sim in the phone for almost 2 years and after ios 17.0.3 update my phone does nog work. The sim work if i put it in another phone but not is my iPhone xs max This is not the service I expect from apple it is pathetic. At this stages I am on my way contacting the ombids man because i do most of my work on that phone and are not able to do it at this stage