Delivery mix up. No one seems willing to help.

I booked parcels for collection on 15/12/2025. The parcels were only collected on 23/12/2025 after numerous texts and follows up. This was even after I instructed them to cancel the collection. The parcels were delivered on the 24th but they were not my parcels. They mixed up the deliveries. I informed them the same day but the issue is still not resolved. I have no idea where my parcels are and I am stuck with someone's parcels. Their contact centre keeps ignoring my messages. This is the worst service ever. What's so difficult with tracing my parcels? The parcels I have were collected at the same place with my parcels.