Sorry to hear you're struggling to get in touch with us on the phone. As you are receiving the 'Refreshing SIM data' message,
Please can you try going to: Settings _ Connections _ Mobile Networks _ Access Point Names.
Got to the three dots at the top and choose Reset to Default.
As the coverage cheker states the coverage is fine, have you also tried using your SIM in a different handset to rule out the possibility of a faulty handset?
Kind regards,
Serena