Consistently Slow Internet Speeds Despite Troubleshooting

I am experiencing extremely slow internet speeds. Despite multiple tickets and repeated troubleshooting steps (rebooting, unplugging, and retesting), there has been no improvement.

I am subscribed to a 100Mbps uncapped LTE combo line but am consistently receiving an average speed of 4Mbps, occasionally reaching 10Mbps. Initially, speeds were between 30-40Mbps, which was satisfactory for my needs such as phone use, console updates, and 4K streaming. However, the current speeds are insufficient, forcing me to choose between these activities.

Receiving only 10% of the service I pay for is unacceptable. Despite purchasing a receiver to boost the signal, speeds remain suboptimal (below 1Mbps without it).

I look forward to your prompt feedback and resolution to improve the internet speed.

Thank you