Heathrow refuses to refund me for pod parking problems

I had to use a shuttle bus, which took longer and was inferior to the premium service I had bookedThree months ago I arrived at Heathrow to discover the pod parking I had pre-booked was not working. Instead of being transferred to the terminal by a pod I had to take a bus, which took longer and dropped me further away from departures. I emailed the company to ask for a refund of the difference between the pod parking and long-stay parking. This was refused and two subsequent letters to the chief