Invoice query & poor after sales service

I was billed for unreturned hardware that Vox were meant to make arrangements to collect, but never ever did. I had to contact them [check the recordings] and they indicated that somebody would make the necessary collection arrangements with me. I want the charge reversed and credited immediately. I refuse to pay for something that I had to follow up on and still hasn't been done. I have made 3 calls to them today to enquire. On my first call I got through to someone and they proceeded to put me on hold then back into the automated Q and I ended up waiting on the line for over 10 minutes. Second call, no response. Third call, currently waiting for someone to answer. This service is atrocious and I fail to see why I have to now run around, follow up, waste my employer's phone bill on something that should have been done months ago when my installation was completed. The technician did not uplift the old hardware when he was on site.