Poor home internet speeds

I was previously on a gigabit plan and am now on a half gig plan. In both cases my download speed has always maxed out under 100mps. A technician recently visited and increased my speed to almost 400mps with a phone call. It’s been a few weeks and it is once again capped at 90mps. I wfh so need to know if telus is capable of delivering the service they’ve been charging me for.