Parcels undelivered

I ordered stuff online on the 21 December 2022, they were supposed to deliver on the 23rd following their call. I waited the whole day and they did not come, I kept calling them and sending emails all in vain. They then decided to deliver some of the stuff only on the 5th of January 2023. I made them aware that there is another parcel missing, I was told it will be delivered the following Monday. Till today I have not received my other two parcels. I am confused I don't know what is happening and whom to talk to. I have never come across this, they are useless I don't understand why they are still in business.