Home Choice

I have been receiving calls from Home Choice, and the agents are looking for someone who clearly owes them. I have explained number of times that they are phoning the wrong number. No matter how many times I explain that they have the wrong number and even ignore their calls as I am tired of explaining myself, but they keep on calling. I used to even receive calls from them during level 5 lockdown. I am even considering reporting them to the relevant bodies including the ombudsman. The question I am asking myself is which number did they initially use to conclude the transaction with that person and why they do not use the same phone number to get hold of that person.