IPHONE 7 MIC STOPPED WORKING AFTER SOFTWARE UPDATE

OK so I got my daughters Iphone 7 when she upgraded to X (im just a poor old fogie, dont judge :-) ), it will let me ring someone and it takes incoming calls but it seems I cant hear anyone nor can they hear me, no error messages or disconnect.

Did notice during a call that the speaker button was greyed out if that helps, it has had a full factory reset.

I understand from Technology News and the watchdog that Apple was aware of this problem back in 2018 but it seems you have done nothing to rectify your mistake, I am a shielded adult locked down due to chronic illness and I am struggling to get things done without a telephone, this issue is your fault and I am hoping that you can rectify the problem for free due to errors from your update.

https://www.macrumors.com/2018/05/04/apple-aware-of-iphone-7-mic-issue-ios-11-3/

I look forward to hearing from you

Thanks in advance for any help with this conundrum