How long is it OK to have phone service without dataplan?

I have post paid 3 line Go5G Plus plan with T-mobile paying $170 per month. Since May 25th one of the lines stopped connecting to internet and after reporting this issue with T-mobile there is no resolution for more than 3 days.
I have wasted more than 10 hours talking to customer support and their technical support with no resolution.  
Internet access is very critical in today's world and service provider should be accountable for disruption like this when there is no natural disaster.