Continual harassment

I have had the misfortune to be assigned the same telephone number as an ex-employee that left our company 18 months ago. Over the past nine months I have received repeated phone calls from African Bank asking to speak to this person - sometimes up to five times a week. <br> <br> Every single time I have explained that the person no longer works for the firm, I have put them through to our HR department that explained to them that we do not have any forwarding details for this person but yet the phone calls just do not stop! <br> <br> I have managed to find this person with a simple search on LinkedIn - why can't they do the same? Please stop calling me!