Service issues

We have had Virgin TV and broadband since telewest days. But since June this year. We have had no end of problems with the service pixelated screens. Programs that stutter. Broadband that just drops out.
Each time I call the service centre they arrange an engineer to turn up. They come they look. Then say there is an issue at a box or something else. Then another engineer turns up and slates the other engineer saying he don't know what he is talking about, Tuesday this week gorging sent a senior Engineer. Who has been with the company 18 years. And decided to install a booster outside my house. But he did not know how to do it so called another engineer and arranged to come back yesterday Wednesday. They fitted the booster which is now powered from my electric. But guess what. The problem is still there. Called Virgin last night and now told another senior engineer will come out Saturday. Now seriously losing the will with Virgin. As cannot solve the problem. Since June. Will be calling again today with ref to terminating the contract. We have 3 TiVo boxes , 1 V+. And a 200mb broadband. Which at max is 30mb. Seriously feed up with lack of service