Frequent disconnects

After 4 years of almost perfect service with the Blast 300 package I upgraded to Gigabit speed and since installing TJ modem the internet drops every 30 mins even after spending 90 mins on the phone with tech support. I can stuck in an endless cycle of calling tech support and then sending a reboot signal. Internet is critical to my ability to meet my work deliverables and I am at my wits end. Can this issue be escalated. It appears to be a reoccurring theme with Xfinity with no resolution.