Terrible Customer Service!

I ordered extra shelves for my fridge at the beginning of January. They sent the wrong shelves and I'm still waiting for them to collect and deliver the correct shelves 6 weeks later, despite following up repeatedly. When I asked for feedback, I was told that I just need to wait since I'm not the only customer they're dealing with. I asked to speak to a manager but they would not give me a contact. I then called their call centre and asked for a manager or team leader to call me. It has been three days, no one has called, and I've still had no feedback. Terrible customer service!